UNIVERSITY MEDICAL SCHOOL OF DEBRECENCENTRE FOR EDUCATIONAL DEVELOPMENT

UNIVERSITY HANDBOOK OF INFORMATICS

1DR. LÁSZLÓ AGÓCS

INTRODUCTION TO MICROCOMPUTERS(MANUSCRIPT, UPDATED VERSION)

Table of Contents

1.1 Introduction......................................................................................................................

1.2 Fundamental Concepts......................................................................................................

1.3 Construction and Operating System of IBM PCs...............................................................

1.4 Norton Commander..........................................................................................................

1.5 Computer Networks..........................................................................................................

1.6 Dictionary........................................................................................................................

1.7 Glossary...........................................................................................................................

1.8 The Hungarian Keyboard (Used at the DOTE)..................................................................

1.9 The IBM Character Set.....................................................................................................

DEBRECEN, 1995

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1.1 IntroductionNowadays computers can be used almost in every field of our everyday life. In this so called "information age", computer means a revolution in communication. In former times we talked about "computing" or "computational technique" but nowadays we rather use the term "informatics", which indicates the changing role of computers. At the beginning people used computers mainly to compute something but now we use them mostly to store, process and retrieve information.

Computers in Everyday Life

Word processingComputers can be used as a very intelligent typewriter. With a word processor program you can type in your text in the same way as with a typewriter but you can store it on magnetic disk, retrieve it later, correct the mistakes, change the order of the sentences, etc. Spelling checkers check the words in your document and thesaurus programs suggest alternative words. Dictionary programs give the explanatory or meaning of the words. You can freely format characters, paragraphs and divisions and make a press-ready copy on a laser printer. Desktop publishing systems are designed to format sophisticated documents as a book or a newspaper.

Database ManagementComputers can store numbers in the cells of their memory. These numbers represent not only ordinary numbers but also real numbers, characters, program commands. Each cell can contain a number among 0 and 255 and this information unit is called 1 byte. 1 kilobyte=1024 bytes and 1 megabyte=1024 kilobytes. The characters are coded with numbers (e.g., A=65). On a CD-ROM (which is an ordinal compact disk and a special drive), or a hard disk drive (high capacity special magnetic media) with a storing capacity of 600 megabytes, you can store 600x1024x1024=629,145,600 characters. That equals to the text of about 600 books! You can not only store this fantastic quantity of information but you can search for data very quickly with a database management system.

CalculationNevertheless, computers are applicable computing and calculating things. Spreadsheet programs stores the numbers, formulas or texts in two dimensional tables. If you type in formulas (e.g., statistical functions) and change the numbers, the computer recalculates the full table. The sophisticated statistical programs (such as SPSS, BMDP) can perform a variety of complicated statistical analysis.

Computer GraphicsRepresentation of data in graphic format is very important when illustrating something. Spreadsheet programs include a graphic program that can draw diagrams with the data contained in the table. There are programs to make charts, freehand drawings, and to manipulate drawings or photographs loaded into the memory by scanners. The new generation of computers (the so called multimedia computers) can digitize the pictures in real time so they can store moving pictures from the video signal of cameras.

GameCertainly, the computer is also applicable to play exciting games. These games are new computer games or simulations of real games (e.g., chess, card games, pool, football, etc.). As G. Kemeny - who is Hungarian by birth and developed the BASIC programming language in the United States - said: The games have an important role to get over the beginners' aversions to the computers.

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Computers in Medicine

Patient DatabasesComputers are used to store the patients' personal, data, medical history, laboratory results, etc. The pieces of information can be coded by numbers to identify the symptoms, disease and interventions, etc., precisely and up-to-date, so doctors can access information very quickly. The management of the health institutions and the social insurance system can control the costs of the treatment.

MonitoringIn an intensive care unit, computers can monitor the patients' physiological functions when connected to the monitoring equipments. In such cases, computer evaluates the circumstances and alerts the physician if it is necessary. Pace-makers, hearing aids, artificial limbs, kidney machines have all been computerized.

Laboratory systemsMost of the modern laboratory equipments contain a built in computer system to store and analyze data; the computer accesses to the data on-line without human intervention. The doctor gets only the results or they appear in the patient database immediately.

Signal and picture processingComputer can read EKGs and by pattern matching, classify them as normal or abnormal. The computer tomography (CT) takes thousands of x-rays slices of body, then combine them into one 3D picture. Future computers will be able to analyze difficult images such as histology sections.

Expert SystemsIf you collect the facts and deductive rules of a certain domain of knowledge and enter them into a logical programming system (such as LISP or PROLOG), the computer would answer your questions. Expert systems can help in decision making (e.g., to make the diagnose), dosing of medicines (e.g., in hypertension or diabetes).

Computers in Science and Research

CalculationComputers are very efficient in processing the results of scientific experiments. You can write your article with a word processor, store the data in a spreadsheet, calculate the results and represent them with a graphic program. The so called integrated softwares (e.g., FrameWork, Symphony, Microsoft Windows) contains all of these program elements. The sophisticated statistical program packages such as SPSS or BMDP can be used to produce complicated statistical analysis.

Simulation and ModellingA computerized model of a real object renders to experiment without any danger and high costs. A computer model consists of some initial states and formulas to predict how the state will change over time under changing circumstances. The results can be displayed in the form of numbers, texts or graphics.

Retrieving Scientific InformationIt is well-known that the quantity of information is doubled in every 5 year. It is increasingly important for the researchers to get systematic information very fast. For this purpose many scientific databases are available with abstracts and even full articles. You can search for data in these databases in an

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associative way, with the help of a keyword system. The most powerful medical database is MEDLINE with the abstracts of more than 3,000 medical journals. It is available also on CD-ROMs.

Computers in Education

TutorialComputers can also store information selected with learning. A tutorial program not only presents information to the students but helps them to choose a convenient way to access it. The new storage devices give a huge mass of information to the student. A CD-ROM can store all medical textbooks with indexes and cross-references, or a computer controlled video-disk contain 54,000 pictures from human anatomy, etc.

Drill and PracticeThe computer is extremely patient with the students. It is an ideal tool to practise (learn) mechanical and boring subjects, e.g., anatomy or languages.

SimulationThere are many simulation programs of real machines and processes, e.g., car driving, flight simulation, etc. These programs make one practice without a risk. In medicine students can practise the diagnose making or treatment processes without any danger. Another type of the simulation programs demonstrates the functions of the body using computer graphics.

NetworkingNetworking means connection of computers to each other. The simplest way to do this is to connect them through their serial or parallel ports via cable or modems (connected to the telephone network).

The local area network (LAN) of a hospital allows you to use the central patient database or achieve the decentralized database of an other ward. The laboratory machines are also connected to the system so their data appears immediately in the patient database.

An up-to-date health service of a country is unimaginable without a well-constructed computer network.

The international networks can be reached over the telephone lines (CompuServe) or via LANs. There are very important scientific networks such as EARN, BITNET, INTERNET, EDUNET. Researchers can write to each other through electronic-mail system of these networks and can use special scientific data banks, etc.

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1.2 Fundamental Concepts

Short History of ComputingIt was a very old desire to automate boring and tiring calculations. This could be realized only in the second half of 20th century, thanks to the development of electronics, industry and the military requirements.

The first mechanical calculator was prepared by LEIBNITZ based on the ideas of PASCAL. In this machine the arithmetical operations were performed by cog-wheels. However, there was a great problem with this machine. If one had to make the same calculation with other initial numbers, he had to repeat all the long procedure. To solve this problem, a new idea was raised: to store this queue of operations: the so called program. Charles BABBAGE designed the first program controlled computer. He used punch cards to store data, and external keys to set up the program. The program was written by Ada LOVELACE (the daughter of Lord Byron). They could not assemble the machine due to the poor industrial background: it was assembled in the 20th century and was proved that it could work.

The punched card was the most popular data storage medium until the recent past. It was applied by Joseph Marie JACQUARD to control his automatic loom in 1808. The technique of processing the punched cards was worked out by Herman HOLLERITH for the American administration. He established the famous IBM Company.

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The automatic loom of Jacquard

ENIAC was the first electronic computer (1944). It was a big monster built from relays and radio tubes. This computer was used by the US Army to calculate differential equations that determine the flight of bullets. UNIVAC (1946) was the first commercial computer.

The concept of the computer was forwarded by John NEUMANN (who was Hungarian by born):

- The computer should be used as a universal machine to solve various tasks.- The computer should be fully electronized.- The parts of computer:

- Central Processor Unit (CPU)- Memory- Input-Output Unit (I/O).

- The programs and data should be stored the same way, and inside the computer.- Binary numbers are required to store program and data.

Evolution of computers can be classified into four generations:

1. generation: vacuum tube machines 1944-1960 2. generation: transistor machines 1960-1970 3. generation: integrated circuit machines 1970-4. generation: LSI (Large Scale of Integration) computers, micros 1978-

Formerly, a computer could run only one program at a time, and only the operators were allowed use it. The development of time-sharing method was a major brake-through from the viewpoint of users. The high capacity computer runs many programs simultaneously, by changing between them very quickly: it seems as if these programs run at the same time. The programs or program sets, the so called jobs have a rank of priority that determines the order of their execution. A job gets the control over the CPU, when the program before it in the queue asks for such an action that does not absorb the CPU (e.g., input-output operation). That is multitasking or multiprogramming.

At the beginning, the users could not work with a time-shared computer directly. The user (programmer) prepared the program on paper and gave it to the operators. They transferred the program to punched cards or paper tape, and loaded it into the computer's memory. If any mistake occurred, the program was rejected. This was the so called batch-processing.

Later, in the multi-user systems, several terminals were connected to the mainframe computer. It made multi-access possible for the end-users. These terminals were simple electric typewriters at the beginning. The user typed in the programs or commands on the keyboard, and the computer printed its messages on paper. These terminals were followed by the cathode-ray tube (CRT) monitors.

The next break-through was the appearing of microprocessors and microcomputers in the later 70s. These cheap machines spread widely. Nowadays these computers have higher operating speed and memory capacity than the former mini- or megacomputers.

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John Von Neumann (Neumann János)

The third important step was networking. The local, metropolitan and long distance networks help us to communicate with other microcomputers, access large databases, to use high capacity mainframes, etc.

Working Concepts of ComputersThe fourth generation computers are designed keeping the Neumann concepts in mind.

The units of the computer are connected to each other through data buses of 8, 16, 32 or 64 bits (wires). Each unit is attached to these lines directly, but the CPU controls the traffic.

The memory consists of cells or registers. Each memory cell represents 1 byte (8 bit). The cells have numbers, and they are called addresses. The content of a memory cell can be a command for the CPU, or a piece of data (ordinal number or character coded by this number) depending on its location.

Schematic, logical sketch of a microcomputer

The microprocessor has few registers that are used only to store the data necessary to run a program. These registers can consist of 1, 2, 4, 8 joined bytes so we talk about 8, 16, 32 or 64 bit processors. A 16 bit processor is faster than an 8 bit one, because the 16 bit bus can transfer twice the data as a 8 bit one in a given time. However, the operating speed of the computer also depends on the width of the external buses, e.g., there are 16 bit computers with a 8 bit data bus (IBM XT), or 32 bit computers with 16 bit data bus (IBM AT). The most important register is the accumulator, that stores data and the results of operations. Microprocessors can perform only simple operations, e.g., it can load a byte to a register from the accumulator, from registers to the accumulator and vice versa. It can add, subtract and compare contents of two registers too.

As we have seen, the memory contains both the program and the data. There are several types of memory used in the microcomputers: ROM, EPROM and RAM. The ROM (Read Only Memory) contains the programs and data that are absolutely necessary for the computer to function. Its content is not changeable, and remains when the computer is turned off. EPROM (Erasable Programmable Read Only Memory) is a special version of ROM. It works the same way as a ROM, but if it is necessary, we can erase its content with UV-light. RAM (Random Access Memory) is used to store and retrieve the application programs and dynamic data of the system. "Random Access" means that all the cells can be accessed in equal time. Its content is lost when you turn off the computer.

The most important peripherals are backing stores that contain the application programs and data. We can load the programs and data from them to the RAM - and in most of the cases -, backwards. These stores are usually magnetic devices (floppy disk drives, hard disk drives) or optical stores (WORM, CD-ROM).

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The other peripherals serve for the communication with the machine. We can instruct the computer, or feed data into it using input devises: keyboard, mouse, light pen, scanner. The computer sends its messages to the monitor or to the printer.

Coordinated working of the computer is ensured by the system of interrupts. The CPU can only do one operation at a time, the other units let it know their needs by sending an interrupt request. The processor ceases the execution of all program in certain time intervals and refreshes the RAM, checks the keyboard and the interrupts. Therefore, the effect of an interrupt request is not satisfied immediately. There is a priority queue of the interrupts and some of them can mask the others.

The computer's "mother language" is binary, but it is not comfortable for the programmers to use it. Instead, they use the hexadecimal (16 based) number system. In this system every byte can be written with two digits. The computer understands only the machine code programs which are queues of hexadecimal numbers. Some of these numbers are commands for the computers and others are the operands of these commands. For example,

A9 00 (in decimal form: 169 0)

instructs a 6502 processor to load a zero to the accumulator register. You can imagine how difficult to build a program with such little bricks. Assembly level programming languages are a little bit comfortable because we can use simple symbols instead of numbers ($ is the shorten form of hexadecimal):

lda $00 (LoaD to Accumulator 00).

The greatest advantage of these languages is, that the programmer can label the steps of the program and use these labels instead of the hexadecimal addresses. The assembly source code can be translated to object code by using an assembler compiler.

The high level programming languages made the programmer's life much easier with their powerful commands. But the large number of them (ALGOL, FORTRAN, COBOL, PL-1, BASIC, PASCAL, FORTH, Clipper, etc.) indicates that they are not universal.

There are two types of high level languages; the interpreter and the compiler type. The interpreter translates the program step-by-step even in the phase of program writing. So the programmer gets the error messages immediately but the running speed is very low because the interpreter translates the program every time when it runs. The compiler first translates the full source code and then runs it. So the speed is higher but the programmer has to wait for the translating. The result of compiling can be machine code or a pseudo-code. In this later case, a linker program is used to organize the machine code, with the help of a routine collection called library.

Programming is very simple when using high level languages, but execution is much slower. However, it is a hard work programming in assembly. There is an intermediate level (e.g., the C language) that mixes the advantages of these two levels. Its data structure is very close to the registers of the computers, so a C program runs very fast. It has a powerful high level command set so programming is easier than in assembly language.

The "physical" parts (mechanisms, electronic circuits) of a computer are called as hardware, in contrast to the "intellectual" part (input-output systems, operating systems, application programs, documentation, etc.), which is termed as software. We often do not know what task is served by the hardware or by the software, and this is not important at all.

Recent DevelopmentsNowadays the so called fourth generation programming languages are used to prescribe all the details of the resolution (the algorithm), so the problem is solved by the programmer and not by the computer. The machine "only" executes the orders of the programmer. The goal of recent developments is to make the computer capable of problem solving. This fifth generation or logical programming languages (LISP, PROLOG) can store the data and the rules of deduction, so they can answer to the users' questions.

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There are two major disadvantages of the fourth generation computers. The first is, that only the numerical calculations are relatively fast, but text or image processing is very slow. These machines are not really suitable to solve such problems as "understanding" sentences, translating texts to another natural language, controlling robots, etc. The second problem is that the development and maintenance of programs are very time-consuming, and adapting a program from a machine or a programming language to an other is very difficult.

There are several attempts to solve these problems and are summarized under the development of the fifth generation computers.

One possible way is, to design and produce much more complex electronic circuits with the VLSI (Very Large Scale of Integration) technology. The second is parallel computing with using of more than one processor in the computers or connecting several computers to each other. The third is to use optical elements in the computers.

The problems of software development can be solved either using structured, modular or object-oriented programming techniques, or by using the new functional or logical programming languages such as LISP, APL or PROLOG.

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1.3 Construction and Operating System of IBM PCs

History of IBM PCsThe first popular microcomputer was the APPLE II with its famous CP/M operating system in 1979. In the early 80s the microcomputers based on 8 bit microprocessors (8080, Z80, 65xx) could not satisfy the users' demands. Then, IBM (International Business Machines), the largest computer manufacturer of the world, came out with its Intel 8080 16 bit processor personal computer: the IBM PC. Its first appearance did not differ from the 8 bit home computers with 8 bit data bus, 4.77 MHz clock signal, 64 kbyte of RAM, built in BASIC interpreter in its ROM, magnetic cassette backing store, etc. Anyway, the construction of this machine made it possible to add more RAM and a floppy disk drive, too.

The next version was the IBM XT, the first computer equipped with a hard disk drive. This computer and its operating system, the MS-DOS (MicroSoft Disk Operating System) became an international standard. Its fantastic spreading origins from two sources. The first was that IBM could take maximum advantage of its well-established market and it absorbed the capacity of the software companies for a long time. The second reason was the simple and open architecture of the machine. IBM obtained the parts of its machine mainly from other firms. The processor was delivered by Intel, operating system and BASIC interpreter was developed by Microsoft, the disk drives were manufactured by Seagate and Tandon. Patent laws protected only the ROM BIOS. The computer could be built up from simple 8 bit catalogue integrated circuits, so many manufacturers (e.g., on the far east) began to produce its duplicates, the so called clones.

As we said above, the IBM XT could use hard disks (fixed disks or winchesters are synonyms). These equipments with their very short accessing time and high storage capacity (2-25 Mbyte) made its applications in business and industry possible. Then the new 8 MHz 8086 microprocessor appeared. The 8087 arithmetical co-processor made the arithmetical operations faster.

IBM AT contains the Intel 80286 microprocessor with 32 bit registers and a 16 bit data bus. The AT 386 came out in 1987 with a real 32 bit 80386 processor that has a 32 bit data bus and an advanced command set. The 386SX computer has a 386 compatible processor with a 286 bus architecture. It was followed by the 64 bit AT 486, and the high performance 486DX2 processors. This later processor is the fastest in the world in its own category. Nowadays these machines are the most popular personal computers along with an other generation of computers: the Motorola 6800 processor based computers, such as ATARI 520ST, 1040ST, Commodore Amiga, APPLE Macintosh. In 1988, IBM began to produce its new personal computer: the PS2 (Personal System 2). This series was not so successful, because of its closed architecture and relatively weak performance, in contrast an AT386 or 486. Now a new AT usually has 4-16 Mbyte RAM and 200-600 Mbyte fixed disk, with a processor made by the Intel, AMD or Cyrics. The newly developed processors (Pentium, PowerPC) have an increased speed but these machines are very expensive. In these days the 100 Mhz 486 DX4 processor has the best performance/speed ratio.

Paralell to the development of the processors, three very important operation systems came out in 1994 and 1995: the OS2 Warp and the Windows 95 for the IBM PCs and IBM PowerPCs and the new version of the Apple operating system for the Power Macintosh machines. These are completely 32 bit operating systems with real multi-tasking facilities.

Construction of IBM PCsThe processors of XTs can address 1 Mbyte of memory, the maximum size of RAM is 640 kbyte. The 80286 processor can address up to 1 Gbyte, but in most of the cases it is used as a 8086

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processor with similar addressing mode. Only the 386 and 486 processors provided the economical and conformable usage of RAM above 1 Mbyte possible.1

The IBM PC has a modular construction. The most important part is the mother board that contains the microprocessor, ROM and RAM. There are a few (4-8) expansion slots on the mother board to hold the modular cards:

Address (hexadecimal) Size 00000 +--------------------------------------+ ¦ ¦ ¦ ¦ ¦ Free RAM ¦ ¦ (256-640 K) ¦ ¦ ¦ 640 K A0000 ¦--------------------------------------¦ ¦ Screen controller ¦ 64 K ¦ ¦ ¦ ¦ ¦ ¦ B0000 ¦--------------------------------------¦ ¦ Monochrome screen (4 K) ¦ 32 K ¦ ¦ ¦ ¦ ¦ ¦ B8000 ¦--------------------------------------¦ ¦ Color graphic screen (16 K) ¦ ¦ ¦ C0000 ¦--------------------------------------¦ ¦ ROM expansions ¦ ¦ ¦ 216 K F6000 ¦--------------------------------------¦ ¦ ROM BASIC ¦ 32 K ¦ ¦ ¦ ¦ ¦ ¦ FE000 ¦--------------------------------------¦ ¦ ROM-BI0S ¦ 8 K FFFFF +--------------------------------------+

Memory distribution of IBM PCs

- Screen controller card: contain the RAM necessary to store the screen information and the electronic circuits to produce the video or RGB signals for the monitor. There are a few popular types of it:

- Monochrome card: produces only alphanumeric characters (numbers, characters and symbols) on the screen so it is suited only to use in offices. Its screen contains 25 rows and 80 columns.

- CGA color graphic card (Color Graphics Adapter): is not only applicable in text mode (25x80 or 25x40), but in graphics mode also, where each pixel of the screen can be controlled separately. Its graphics resolution is 640x200 with two colors or 320x200 with four colors.

- Monochrome graphic card (Hercules, MGP): has a better resolution (720x348) but only in black and white.

- EGA color graphic card (Enhanced Graphics Adapter): has 640x380 resolution with 16 colors. It is compatible with the CGA adapter because it can display graphics of low resolution, too.

1 It is very irritating that although our machines usually contains 4-16 Mbyte of RAM, accessing the memory areas above 1 Mbyte is very difficult. We need a special driver program to do this and there are two different standards for handling this memory (EMS and XMS). Formerly the new programs were expected to run on the older (XT) machines as well and that was a strong limitation in development. Only the latest operating systems (Windows, OS2) can make the most of the 32 bit bus architecture.

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- VGA color graphic card (Video Graphics Array): gives the best graphics with 640x480, 800x600 (standard VGA) and 1024x768, 1280x1024 (super VGA) resolution with 256 and millions of colors.2

- XGA color graphic card (eXtended Graphic Array): gives the highest possible resolution (1280x1024) in 16 million colors. This type of cards is quite expensive, and are not used widely yet.

- Disk controller card: controls the floppy and hard disk drives.

- Input-output card: usually contains a serial port (RS-232 standard) and a parallel port (CENTRONICS standard). Two parallel ports (LPT1, LPT2) and two serial ports (COM1, COM2) can be used in the same time. Serial ports usually are connected to the mouse, another computer or phone modem and parallel ports to printers.

At the beginning a standard AT had a:

- motherboard with 80286 and 1 Mbyte of RAM,- CGA card,- I/O card with one serial and one parallel port,- disk controller for the floppy and hard disk drive,- 8 expansion slots,- 1.2 Mbyte floppy disk drive,- 20 Mbyte hard disk drive,- 200 W power supply unit.

Nowadays, ATs can handle 40-600 Mbyte winchesters (thank to MS-DOS 4.00 and higher versions) and 2-8 Mbyte RAM. 386SX, 386 and 486 PCs use 32-256 kbyte cache memory to make disk operations faster.

In XT's, hardware configuration can be set up by dip switches or jumpers. In ATs there is a CMOS-RAM fed with an accumulator to store the configuration data. It can be changed with the setup program.3

IBM PCs can control several disk drives marked with the letters A, B, C, D, E... The first drive is the floppy disk drive marked with "A". It is absolutely necessary to install the machine. The second optional floppy disk drive is marked with "B". First hard disk drive is indicated with "C". The other

2 These SVGA cards need 2 Mbyte of RAM on board, fast bus access (at least VLB=Vesa Local Bus), and expensive high resolution monitors. 3 You can start the setup program by holding the <Del> or <Esc> keys pressed while the machine is starting. It is inadvisable to use this program for a beginner. If you are a more advanced user you can change the major settings of your system (type of the floppy disk drives, type of the hard disk drive with autodetection, password checking, etc.) The way of usage is written in the mother board manual but if you do not understand anything call a specialist.

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Floppydrives

Keyboard

Monitor

Appearance of an IBM PC

letters (D, E, F, etc.) can indicate further fixed disks or logical disks. For example the first hard disk can be divide into to logical disks with the letters C and D or you can create a RAM-disk in the memory with the letter E which behaves the same way as a real disk but exists only until the power is on.

Earlier, XTs could only handle 360 kbyte floppy disks but with modern controllers they can handle 1.2 and 1.44 Mbyte disks, too. ATs contain one or two 1.2 Mbyte floppy disk drives which can be used in 360 kbyte mode also. Unfortunately, there are a lot of compatibility problem with these two types of floppy disks.

The 5 1/4 inch floppy disk is divided into concentric sectors and blocks with the size of 512 byte. There are two magnetic heads in the drive below and above the disk. The 360 kbyte drives can use DS,DD (Double Sided, Double Density) disks. The 1.2 Mbyte drives work with special PC-AT compatible, or DS,HD (Double Sided, High Density) disks. (They also can use the DS,DD disks in 360 kbyte mode.)

Floppy disks can be easily damaged. User should not touch the disk surface with hands and should not bend them. It is advisable to put them back into their cover after removing from the drive. If you want to prevent data from accidental erasing you can stick down the write protect slit.

The new 3 1/2 inch floppy disks developed by SONY have a hard (metal or plastic) cover. They have a storage capacity of 720 kbyte (DD) or 1.44 Mbyte (HD). It seems that the new international standard for data storage tends towards 1.44 disks.

Hard disks are similar in size with floppies, but their magnetic coating is finer, more complicated. The thin metal based laps, which contains a magnetic coating, are place in vacuum. Depending on the storage capacity and data access speed, several laps and reading/writing heads are included in one HD. Due to the high quality magnetic coating and sophisticated head moving mechanics very high data density can be produced on them. Nowadays the 20-40 Mbyte hard disks are counted as low capacity because the new machines have 200-600 Mbyte winchesters.

A new disk cannot be used at once. First you have to create the structure of data storage blocks. This is called as formatting. After this you can write the programs or data on the disk to sequences of bytes: to the so called files.

The box of the computer also contains a power supply unit with 150-250 W output.

The monitor is a stand alone unit that is usually placed on the computer itself. The screen controller cards produce the signal for the monitor.4 They can be operated in two ways:

- Graphic mode: the graphic card stores the brightness and color information of all pixels.- Character mode: the graphic card store only the code number of the characters. There is a

standard for coding characters called ASCII-code (American Standard Code for Information Interchange). It binds the characters to numbers among 0 and 127. The IBM character set contains special symbols, international characters and line drawing signs which are coded from 128 to 255. The character generator produces the bit map of the characters using the stored codes. The CGA-card uses 8x8 matrix, the EGA and VGA have 8x14 bit map and the Hercules works with 9x14 pixels.

4 It is an NTSC standard (American, Japanese) video signal with 60 Hz frequency.

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5 1/4 inch floppy disk

Nowadays the VGA cards and monitors are regarded as a standard (640x480 pixels with 16 or 256 colors). The 256 color bitmap means that the color information is stored on one byte for each of the pixels. The true color presentation needs more memory (two or three bytes for each of the pixels). The usual memory sizes of the graphic cards are 512 K, 1 M or 2 M.5

The user can communicate with the computer through the keyboard. It has three main parts: the function keys, the typewriter fingerboard and the numeric keypad.

Most of the programs assign similar tasks to the function keys. For example F1 gives the help page almost in every case.

The left hand side part of the keyboard is the same as an American typewriter but there are three alternate keys (<Control>, <Alt>, <Shift>) to alternate the effect of the other keys, if they are pressed in the same time. The <Enter> key is used to "enter" the commands typed in into the computer. <Backspace> clears the character on the left side of the cursor. <Caps Lock> chooses the capital letters.

The numeric keypad on the right side makes typing of numbers easier. If you press the <Num Lock> key the numbers will appear, otherwise the cursor control keys will be effectual. These control keys on some of the keyboards are duplicated.

Keyboard of IBM PCs

The function of the special keys is as follows:

<Left arrow>: moves the cursor left.<Right arrow>: moves the cursor right.<Up arrow>: moves the cursor up.<Down arrow>: moves the cursor down.<Insert>: inserts a space or changes the overwrite/insert mode.<Delete>: deletes the character under the cursor.<Home>: moves the cursor to the first character of the line.<End>: moves the cursor to the last character of the line.<Page Up>: moves the cursor to the previous page of text.<Page Down>: moves the cursor to the next page.<Escape>: returning ("escaping") from a part of the program.<Print Screen>: prints a hard copy of the screen on the printer.<Pause>: freezes the screen until pressing any other key.<Ctrl> +<C>: aborts the execution of the program.

5 The quality of the monitors depends on the physical pixel size, mass-produced monitors have a 35 mm pixel size, better screens are built up from 28 mm pixels. It is worth buying NI (Non Interlaced) and LR (Low Radiation) monitors because they do not constrain your eyes. The diameter of the normal screens is 14 “, but you need larger (17-20 “) monitors for speccial applications such as desktop publishing, image processing, etc.

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Function keys

Numeric keypadCursor controll keys

Typewriter keys

<Ctrl>+<PrtScr>: echo the screen on the printer (second pressing turns off echoing).

You can access only the characters between 32 and 127 with a normal keyboard. The characters above 127 can be typed out with pressing <Alt> and then the ASCII-code on the numeric keypad. There are also special programs to redefine the keyboard such as KEYBHU.COM or MPXW.COM for the Hungarian characters. You can see the IBM character set in Chapter 1.9.

The mouse, as an input unit, is used worldwide. One can move the cursor with a mouse on a very comfortable way and can choose from the menus or icons with a simple click. Mouses can be connected to the serial port (COM1 or COM2) and you have to install a mouse driver program in the AUTOEXEC.BAT.

The mouses usually are equipped with three keys but the PC programs use only the left key and rarely the right one.

Scanners are used to scan pictures and fill the data into the memory as a bitmap. The popular, inexpensive handy scanners can scan only in stripes of maximum 10 cm width. Page scanners can be fed with at least A/4 size sheets.

The resolution of the scanners is given in dpi (dot per inch): e.g., 300, 600, 1200, 2400 dpi.

You can store your images in several file formats (e.g., TIF, GIF, PCX, BMP, IMG, JPEG, etc.) The file size of the high resolution images is very large that is why a few of this file types store the information in a more or less compressed form. (They use only simple methods to compress-decompress the image because the more sophisticated methods are very slow.)

However, if you scanned an image you got only the bitmap copy of it. If your sheet contains printed text, you need a sophisticated OCR (Optical Character Recognition) program to produce the text (character) form of this image. One of the best OCR programs worldwide is the Recognita developed in Hungary.

Printers usually should be linked through the parallel port. Nowadays three types of printers are in use: the dot matrix, the ink jet, and the laser printers. Formerly, daisy-wheel and golf-ball typewriters were often used as printers because of their high quality letters. But they were too slow and could not produce graphics so the laser printers elbowed them out.

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Mouse

Handy Scanner

Dot matrix printers have 9-24 pins that strike the bitmap through a ribbon to the paper. They can print characters and graphics, too. Most of them can be fed with both continuous paper and single sheets. In this later case one should feed the paper manually or automatically using an optional cut sheet feeder. Printers equipped with narrow carriage can print 80 characters in a line, ones with broad carriages can print 135 characters.

EPSON printers are the most popular matrix printers throughout the world. The most popular EPSON is the FX-1050 (broad version) and FX-850 (narrow version). It is very simple to use these machines.

When you turn on the computer, the printer gets into the on-line state (the on-line indicator goes on, the printer is ready to print). If you press the ON-LINE button the printer will turn to off-line state. Then you can advance the paper one line by pressing LINE FEED and with a full page by pressing FORM FEED. The LOAD/EJECT button serves for loading or ejecting the paper.

The printing quality also can be selected using the control panel of the printer. There are three characters sets: the simple draft and the two NLQ (Near Letter Quality) sets (Roman and SansSerif). Printing in draft mode is faster than in the others but the quality of the print is poor. The thickness of the characters can be preset in three modes. The normal setting is 10 cpi (character/inch) when the machine prints characters 0.254 inch of width. In the 12 cpi mode the characters have a little less width. The proportional printing means that the characters have different width. There is an other possibility to print more character to a line: the condensed mode with its small letters.

There is an arm on the top right side of the printer which is used to select between the continuous paper and single sheets. The continuous paper should be thread into the cog-wheels on the top of the printer. By pressing the LOAD/EJECT button, paper will be loaded automatically. Pressing of the ON-LINE button has the same effect if the printer is not in on-line mode. When printing has finished, the printer feeds the paper with a few lines to make detaching possible. If you would like to use single sheets it is not necessary to remove the continuous paper. You can thread out the continuous paper by pressing the LOAD/EJECT button and later you can thread back it with the same button.

There are two sets of dip-switches on the right side of the printer. They are used to set up printing parameters that are rarely changed. For example, the international character sets, enlarged or condensed printing after turning on the printer, automatic format feed at the bottom of the page, etc.

Unfortunately, the international character sets do not contain all the special Hungarian characters and they can be downloaded only in draft mode. Therefore, the character ROM usually is replaced with an EPROM in our country. Recently, all EPSON and STAR printer sold in Hungary contains the full Hungarian character set.

The printers of the EPSON LQ series work with 24-29 pins so their prints have a better quality than the FXes, they give the so called letter quality (LQ).The working concept of the laser printers is similar as the xerox-machines (electrostatic copiers) but they get the signal not from a scanner but from a computer. There was a world standard for these printers: the HP (Hewlett-Packard) LaserJet Plus compatible printer and now there is a new standard: the HP LaserJet III compatible (or HPPCL-5 compatible) machine. All the printers should emulate one of these operating modes.

The resolution of the laser printers is among 300 and 600 dpi. They work in two different ways. In the first case (when printing graphics) the computer produces the bitmap graphics and sends it to the RAM of the printer. In the second case (when printing texts) the computer first downloads the bitmaps of the characters to the memory of the printer and then, when the printing is in progress, the computer sends only the codes of the required character sets and characters. These downloaded fonts

16

Dot Matrix Printer

Laser Printer

are also called as soft fonts and should be distinguished from the hard fonts that are built in the ROM of the printer, or can be loaded from a plug-in ROM-cartridge.

The base memory was usually 512 kbyte that was not enough to print a full page of graphics. The new HP III series comes with a RAM of 1 Mbyte. If the printing speed is not satisfactory, it can be increased by adding more memory (2-4 Mbyte).

The default paper size of this printers (and the word processor programs) is the Letter (8.5x11 “ American size) but in Europe we use A4 size (8.27x11.69 “ or 210x290 mm) papers. Bad paper size setting may cause different printing problems. Use the laser printers with high quality Xerox papers only!

The quality and the costs of the ink jet printers are between the matrix and the laser printers. Their working concept is very interesting: they shoot ink drops to the paper from one or more jets continuously. In this case the print is built up by the drops likewise in a matrix printer by the pins. The only difference is the high quality of the print produced by the jet printers. This method is applicable for producing color printouts. The new version of these printers is called bubble jet printer and it produces better quality printouts than a laser printer.

There are special glossy papers, transparencies, labels for using in laser printers and ink jet printers. Other materials can damage the printers.

Plotters use color pens to draw the picture. Therefore they are suitable in CAD (Computer Assisted Design) applications to draw the plan.

The Operating SystemThe basic part of the operating system is the ROM-BIOS (Basic Input-Output System) which is placed in the upper 8 kbyte segment of the memory. It contains the programs and tables that are absolutely necessary to operate the computer. After the computer is turned on, the ROM-BIOS checks the memory, the keyboard and runs the setup program if it is requested. Finally, it attempts to load the disk operating system to the RAM from one of the backing stores.

The other part of the operating system can be found on the disk. This is the DOS (Disk Operating System) which can be either from the Microsoft Co. (MS-DOS) or from the IBM Co. (PC-DOS). The name "DOS" comes from the "disk" in two senses: the DOS is placed on a disk and its main function is to handle the disk files.

The ROM-BIOS checks the disk drives in their alphabetical order (A, B, C, ...). If there is a special disk containing the operating system in drive A, it will be loaded. If there is an ordinal disk in this drive the system will halt with the "Non system disk" error message. If drive A is empty, the computer will try to load the system from the next (B) drive and so on. If the computer is equipped with a hard disk drive, usually the OS can be found on it.

The system disk contains a short boot sector that can load the operating system.6 ("Boot" comes from "bootstrap".) There are two special files on the system disk: IBMBIO.SYS and IBMDOS.SYS. These system files are in fixed positions on the disk and are hidden files. It means that their names do not appear when you ask for the directory of the disk. These names are used in PC-DOS; the MS-DOS equivalents are IO.SYS and MSDOS.SYS. The first file controls the peripherals the second contains the service routines of the DOS. They are also called as resident programs, which means that they always remain in the memory and no program can clear them. After exiting any other program, they become active again.

The most frequently used commands are included in the COMMAND.COM file. These are the so called internal DOS-commands. The COMMAND.COM is a semi-resident program which means that it will get damaged if the other program absolutely needs its place in the RAM. In this later case the COMMAND.COM should be reload after finishing the other program. If the computer does not find the COMMAND.COM, it sends the "Bad or missing command interpreter" message.

6 The boot sector of the floppy or hard disks is the favorite target of the viruses. You can kill them with special programs or you can install a virus protection system that checks the new programs.

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The remaining part of the DOS; the rarely used commands, is called external DOS-commands. They are separate program files on the system disk and they should be load every time you would like to use them.

The data storage structure (logical structure) is universal within a given OS. There is a table, the FAT (File Allocation Table) on each disk that stores the occupation of the blocks and the chaining information of the files (how the blocks of the file come after each other). The files are classified to directories. The main directory, the so called root can contain simple files and directories; these directories can contain other files and directories, and so on.

You can identify the files (and directories) with their name and extension. The filename can consist of maximum 8 characters with certain restrictions (e.g., the first character must be only a letter or a digit, the name should not contain space, etc.). The extension is optional and can be maximum three characters. This extension can be only a notation for a user program. There are some often used symbols (e.g., TXT=text file) but there is no compulsory rule to use them. There are only three extensions which mean something for the operating system: the BAT, COM and EXE extensions are reserved for program capable of running individually; the so called Batch commands (BAT), executable program (EXE) and machine code commands (COM).

The DOS also stores the size of the files in bytes, the time of last updating and some attributes (hidden file, read-only file, etc.).

When the COMMAND.COM has been loaded, the computer searches for some other files, too. First it checks whether CONFIG.SYS file exists. It is a simple text file with the initial parameters of the system, e.g., maximum number of opening files and temporary buffers, name and location of device drivers to handle the keyboard or screen, usage of RAM-disk, etc.

In the next step the computer searches for the AUTOEXEC.BAT file. If it exists, the computer executes the commands listed in this text file. This file is used to set up the prompt, the path, to load some resident programs and to start a user program (See later).

If there is no AUTOEXEC.BAT file on the disk the computer will ask you for the date and time. If they are correct just press <Enter> twice, otherwise type in the date and time in the given form:

Current date is Tue 10-3-1989Enter new date:Current time is 00:00:10.15Enter new time:

Then the actual prompt appears with the letter the drive from which the operating system was loaded:

A>or

C>You can change the actual disk drive by typing in its letter, a colon and then pressing <Enter>:

A> C: +<Enter>C>

Then you can run programs (files with the extension .BAT, .COM or .EXE) of the root directory by typing in their name (without the extension) and then by pressing <Enter>. The usage of DOS-command is the same. For example,

C> DIR +<Enter>results the execution of the DIR command what lists the directory to the screen.

You can use two jokers (wildcards) in every DOS-command. The * sign substitutes all the characters after the mark. The "?" sign substitutes only the letter where it stands. These signs are very useful to select groups of files. For example,

DIR *.* lists all the files.DIR *.COM lists all the files with the extension COM.DIR R*.* lists all the files beginning with R.

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DIR R????.* lists all the files named with 5 characters and beginning with R.

Some Important DOS CommandsOne of the advantages of placing the operating system on disk is, that it can be updated when a new version comes out. (It should be noted that the ROM-BIOS also can be updated by a new EPROM.) The latest versions of DOS are MS-DOS 5.00, PC-DOS 4.00 and DR-DOS 6.00.

DOS commands consist of an identifier and a list of parameters. We shall use the following notations:

d: Identifier of the disk drive (A:, B: C:). If we do not use the command will be executed on the actual drive.\ (backslash) Separator between the directory names./ (slash) Precedes the optional parameters.path Route to access a directory.file, filename Identifier of the file.ext Extension of the file name.[..] Optional parameter. (The brackets should not be typed in!)

We can use capital or lower case letters in the commands but it does not mean anything for DOS. The following commands are all available in MS-DOS versions 3.3 or grater, except a few external commands. We shall indicate this limitation in every case.

Internal DOS Commands

CHDIR, CD (CHange DIRectory)

Changing to another directory from the actual one.

Syntax:CHDIR [d:][path] or CD [d:][path]

Examples:CD DBASE

Selects the DBASE directory.

CD..Gets to the directory of the previous level.

CD\ Gets to the root.

CD\WORDGets to the WORD directory through the root.

COPY

Copying files to an other place (directory or drive) with the same name or duplicating files with different names. Several files also can be copied to one file.

Syntax:

COPY [d1:][path1]filename1[.ext1] [d2:][p2]filename2[.ext2]COPY filename1[.ext]+[filename2][.ext]+...

Examples:

COPY a:help.txt c:\dbase\help2.txtCopies the help.txt file from the A: floppy to the C:\DBASE

directory.

COPY a:help.txt c:\dbaseCopies the help.txt on the same name to the DBASE directory.

COPY a:*.* c:\dbase

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Copies all the files from A: to the C:\DBASE directory.

COPY f1.txt+f2.txt+f3.txtCopies the f2.txt and f3.txt files to the end of f1.txt.

DIR

Lists the directory. It types out the names, extensions and creation date of the files. The names of the hidden files do not appear in the list.

Syntax:DIR [d:][path][filename[.ext]][/P][/W]

Examples:DIR

Lists the directory.

DIR/PIf the screen is full it will wait for pressing a key to continue

listing.

DIR/WLists only the filenames but in the full width of the screen.

ERASE

Erases the files from the directory. The command does not erase the files physically, but marks them only as deleted so they can be reconstructed with the UNDELETE command in version 5.0. If you ask for deleting all the files in a directory the computer puts a control question to you: Are you sure (y/n)? The command deletes only the files and not the subdirectories.

Syntax:ERASE [d:][path][filename[.ext]]

Examples:ERASE *.bak

Erases all the files with the extension .BAK.

ERASE *.*Erases all the files in the actual directory.

MKDIR, MD (MaKe DIRectory)

Creates a new subdirectory.

Syntax:MKDIR [d:]path or MD [d:]path

Example:MD DOC

Makes the DOC subdirectory in the actual directory.

PATH

Path to access files. If you try to access a file that can be found in an other (un-pathed) directory the computer will not find it. If you gave some paths the computer will continue searching in them, too.

Syntax:PATH [d:]path[;[d:]path][;...

Example:PATH C:\DOS;C:\UTIL

Makes searching always possible in the DOS and UTIL directories.

RENAME

Changes the name and/or the extension of a file.

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Syntax:RENAME [d1:][p1]file1[.ext1] [d2:][p2]file2[.ext2]

Example:RENAME letter.bak letter.doc

Renames letter.bak to letter.doc.

RMDIR, RD (ReMove DIRectory)

Removes a subdirectory. It has no effect if the directory is not empty.

Syntax:RMDIR [d:]path or RD [d:]path

TYPE

Types out the content of a file to the screen.

Syntax:TYPE [d:][path]filename[.ext]

Example:TYPE readme.txt

Lists the readme.txt file to the screen.

Batch ProcessingFiles with BAT extension are ordinal text files containing lists of DOS commands. If you start a batch-file with typing in its name, the effect will be the same as you would type in the commands included in the file. As you saw formerly, there is a special batch-file, the AUTOEXEC.BAT (AUTOmatic EXECution BATch file) which automatically begins to run after turning on the computer. We, for Example, use the following AUTOEXEC.BAT file:

@echo off turns off listing of the commands.set path=c:\ms-dos gives the path for accessing the external DOS-commands.set prompt=$p$g sets up the prompt for appearing the name of the actual directory.doskey runs the DOSKEY.COM program.cls clears the screen.ver shows the DOS version number.

The CONFIG.SYS fileAs you know, the CONFIG.SYS is a list of the most important device drivers. On 386 and 486 machines it should be started with the floowing lines:

DEVICE=C:\DOS\HIMEM.SYSDEVICE=C:\DOS\EMM386.EXEDOS=HIGH,UMB

Then you can use for the drivers the upper memory (650 K - 1 M) with the DEVICEHIGH= specification (in the CONFIG.SYS) and the LOADHIGH command (in the AUTOEXEC.BAT). The HIMEM.SYS and EMM386 ensure the the XMS memory handler that is required by the Windows.

External DOS-commandsAs we said, the external DOS-commands are stand alone programs with .COM or .EXE extensions. Therefore they can only be accessed if you are in the DOS directory, or their path was formerly given.

DISKCOPY

Copying a floppy disk to an other. If the target disk is not formatted the program will format it. It copies the system and hidden files, too. Only similar types of disks can be copied to each other (e.g., 360 to 360 k, or 1.2 to 1.2 M).

Syntax:

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DISKCOPY d: d:Examples:

DISKCOPY a: b:Copies the floppy disk in drive A: to the disk in drive B:.

DISKCOPY a: a:Makes a copy to the same drive (the disks should be exchanged several

times).

DOSKEY (MS-DOS 5.00)

Resident program to edit the formerly typed DOS-commands. You can get back the commands to the prompt by pressing cursor up/down and edit them with the cursor left/right, backspace, insert, delete keys.

DOSSHELL (MS-DOS 5.00)

Operating system shell. One can manage the operating system by using menus.

FORMAT

Formatting a floppy disk or a hard disk.

Syntax:FORMAT [d:][/S][/1][/8][/V][/B][/4]

Examples:FORMAT a:

Formats the disk in drive A: to 360 K or 1.2 M (depending on the type of the drive).

FORMAT a:/s/vTransfers the operating system after formatting (/S) and checks it (/V).

FORMAT a:/4Formats a 360 K disk in an 1.2 M drive.

PRINT

Printing of a text-file to the printer.

Syntax:PRINT [d:][path]filename[.ext]

UNDELETE (MS-DOS 5.00)

Reconstruction of the files formerly deleted by the ERASE command. The computer lists the erased files one by one. If you choose a file, the computer asks for the first character of the file-name (because it indicates the erased files with a question mark in the first position of their name). If you write something to the disk after erasing a file, this unerased file can be damaged.

Syntax:UNDELETE [d:][path]

UNFORMAT (MS-DOS 5.00)

Reconstruction of a newly formatted disk. The computer stores a mirror of the disk before formatting and it can repair the disk with these data.

Syntax:UNFORMAT [d:]

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SOME NEW COMMANDS IN MS-DOS 6.2

FORMAT

You can specify the size of the disk, e.g.:

FORMAT A:/F:720 720 Kyte, 3.5 “ floppy disk.FORMAT A:/F:1440 1,44 Mbyte, 3.5 “ floppy disk.FORMAT A:/F:360 360 Kyte, 5.25 “ flopy disk.FORMAT A:/F:1200 1,2 Mbyte 5.25 “ floppy disk.

INTERLNK, INTERSVR

If you connect two machines via their serial ports and you type the

DEVICE=C:\DOS\INTERLNK.EXE

line in the CONFIG.SYS of one of them (and reset this machine), then after starting the INTERSVR.EXE on the other machine, you can access all the disk drives of this computer on the other with, for example, the identifiers I, J, K. This is a very comfortable way to copy large files and installing programs.

MEMMAKER

You can optimize the memory allocation with this program. (It requires a 386 or 486 machine with HIMEM.SYS és EMM386.EXE drivers).

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1.4 Norton Commander

Utility programs make the usage of DOS easier and they also give new services. They have friendly user interfaces with menus and icons to handle the operating system. Beside this, they usually contain simple word-processors and disk monitors. These programs are useful not only for the beginner but also for the advanced users or programmers. There are several integrated utilities (e.g., PathMinder, PCTools or the built-in DOSSHELL of MS-DOS 5.0 and 6.0), but the most powerful and popular one of them is the Norton Commander (and the other utilities designed by Peter Norton). We will introduce the latest (V4.0) version of the Norton commander.

We would like to draw your attention to the fact, that due to screen capture necessities, we had to run the Norton commander through MS Windows. The title bar containing the "NC" text on the screens of this chapter, is added by the Windows program itself.

The Norton Commander is a resident program, and can evoked from the AUTOEXEC.BAT also (the main program is called NC.EXE). The DOS prompt can be accessed directly from a Norton Commander session, and this feature is one of the great advantages of this application. Therefore one can use both the commander and the original DOS-commands simultaneously. Anyway, we suggest to acquire the most often used DOS-commands such as DIR, CD, MD, RD, COPY, ERASE FORMAT, etc., because utility programs are not available on every computer, and the DOS commands can be more powerful in certain cases. The program can show the disk directories in two windows, and the main menu at the bottom line of the screen:

F1 Help helps how to use the program.F2 Menu opens the user defined menu system.F3 View displays file contents without editing facility.F4 Edit starts the simple word processor to edit the file.F5 Copy copies files.F6 RenMov renames or moves files.F7 Mkdir creates a new directory.

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Starting screen of Norton Commander

F8 Delete deletes files.F9 PullDn switch on the pull down menu system.F10 Quit exits from the program with setting the memory free.

You can choose between the two windows by pressing the <Tab> key. If you move the cursor to a directory name and then you press <Enter> the directory will be opened.

Pull-down menu system of Norton Commander (Left and Right)With the <F9> key, you can access the pull-down menu. You can choose an item with the cursor control keys and <Enter>.

The "Left" and the "Right" submenus are similar, and are used to set-up the parameters for the left and right windows:

Brief: Abridged show. Only the name of the directories and files will appear.

Full: Full show. The size and creation date of the file also will be showed.

Info: Information about the RAM, the size of the active backup device and directory, and about the free memories.

Tree: Tree structure of the active backing store. It shows the sub directories similar as the branches of a tree. You can move the cursor to any directory and then you can see the content of this directory in the other window (if it is active).

quick View: Quick show of the content of files. Uses both display windows. You can see the file-names of the marked area in one of the windows and the other window sows the content of the marked file. This option is very useful if you would like to identify the files on the evidence of their content.

Compressed file: If there are any compressed files (ARJ, ZIP, LZH, etc.) in the directory, you can automatically select them to view.

linK: Linking of PCs. The Norton Commander makes connection of two PCs through their serial ports possible. In this case you can send and receive messages and you can also read and write the hard disk of the other machine.

On/off: With this command you can switch on or off the display window.

The next block of this submenu can be used to set-up the order of appearance of the files.

Name: Shows files in alphabetic order of the filenames.

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eXtension: Shows files in alphabetic order of the extensions.

tiMe: Shows files in order of the creation times. The first file in line is the one stored latest.

Size: Shows files in order of the sizes.

Unsorted: Shows the files as it is stored in the harddisk.

Unsorted: Restoring the previous order.

Pull-down menu system of Norton Commander (Files)

The next menu (Files) contains the following items in the first block:

Help: Detailed description of usage.

User menu: Activates a user defined menu. You can create a menu contained your most frequently used programs and you can start them with this menu. (See later how to design this menu.)

View: Shows the content of the selected file without the damage of unfortunate overwriting. The text can be moved by the cursor control keys. Norton Commander recognizes the formats of a few popular database management systems, word processors and image formats, so it can show them without the disturbing control characters. There is an opportunity to get the hexadecimal form of the files, too.

Edit: A simple word processor to edit the selected file. Its works similar to the View option, but it can change the content of the file. If you want to create end edit a new file you have to press the <Shift> and the <F4> keys.

Copy: Copying files. It copies the marked file in one of the windows to the directory showed in the other window. You can copy more than one file, too. To do this you have to mark the files with the <Ins> key first. (The second pressing of this key unmarks the file.) If you want to copy all the files of a directory, you have to press the gray <+> key (on the numeric keypad). Pressing of the <Shift> and <F5> key makes the use of * and ? jokers possible.

Rename or move: Renaming and moving file(s). The usage is the same as the Copy option. The move command copies the marked files to a given directory and deletes the original.

Make directory: Creation of a new sub directory in the actual directory.

Delete: Deleting files or directories. Selection of files or directories are similar (<Ins>). You can choose a group by pressing <Shift> and <F8>. If you want to delete the sub directories and it

26

Pull-down menu of Norton Commander (Files)

contents of a main directory, you should check the "Include sub directories" check book too.

file Attribute: Setting up or altering attributes of files (Read-only, Archive, System or Hidden).

select Group: Selecting of files for an operation.

deselecT group: Unselecting the previous selections.

Invert selection: you can invert a selected group of files and/or directories by pressing the "*" on the numeric keypad.

reStore selection: You can restore the inversion of the selection also by re-pressing the "*" key on the numeric keypad.

Quit: Exiting the Norton Commander. This command sets free the whole memory that was occupied by the Norton

The Commands menu gives us some further useful services:

NCD tree: Showing the tree-structure of directories of the actual storage device.

Find file: Showing the localization and creation date of a given file.

History: The program stores all the commands executed since it started. This item gives the list of these commands and the possibility of repeating them.

EGA lines: Setting up more then 25 rows on the screen with EGA or VGA monitors.

system Information: Provides brief information of the hardware components of the computer.

Swap panels: Transposing the contents of the left and right windows.

Panels on/off: Switching on/off the windows.

Compare directories: Comparing the contents of directories.

Terminal emulation: This is a very useful application which allows you to control modem, fax and other serial communication protocols. Using this, you can dial any telephone number automatically, too.

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Pull-down menu system of Norton Commander (Files)

Menu files edit: Editing the user defined menu. First the hot key should be specified (this will activate the menu item) and then the commands similarly as in a batch file. (See the two figures above and the Automenus option later.) You can define a use menu by manual editing of the NC.MNU file. This can be found in the directory specified by the "SET NC=" directory. (See later.) This can be done during the installation process of the Norton Commander too.

Display of the previously defined user menu

eXtension file edit: Giving of extensions for the application programs. For example, if you attach the .DOC extension to the WORD program you can run it by marking a DOC file and pressing <Enter>. After the program starts it will automatically load the given document.

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Creating a user defined menu for Norton Commander

Pull-down menu of Norton Commander (Options)

The next menu is the Options in which you can set-up the initial parameters of Norton Commander:

Configuration: Initial settings of the main program:

Screen colors:1. black & white.2. color 1 and Color 2. (two sets of color schemas)3. laptop (portable computer with an LCD monitor).

Screen blank: Sets the screensaver time limit. After this time the monitor shows the "sky with stars" to take care of the picture tube.

File panel option: Making visible the hidden files. Marking with the <Ins> key.

Tree panel option: Switching of automatic showing of the content of the directory marked in the directory tree.

Other option

Menu bar always visible: always displays the pull-down menu (otherwise you can activate it by pressing <F9>).

Auto save setup: Automatic saving of the above mentioned options. If you do not ask for this item, the original setting will remain after reset.

Left handed mouse: Transposing the keys of the mouse.

Fast mouse reset: Connecting of a mouse with some types of computers (e.g., PS2) can cause a delay of several seconds after a DOS command ran. Using this option can eliminate this error.

Printer port

This option should be specified if you want to print files directly from the Norton Commander. It is advisable to print text (ASCII) files only. You must specify the port (LPT or COM) to which the printer is connected.

Editor: You can select different word processor instead of the built-in editor, which will start by pressing the <F4> key. The built-in editor is too simple, so it is advisable to setup a more sophisticated program at this point, e.g., Norton Editor (NE).

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The Options menu

Confirmation: Using this menu you can specify the commands which must be reinforced by a control command. These commands are Copy, Delete, Move, Delete sub directories, and Exit.

Compression: It is possible to compress files without exiting the Norton Commander. You must copy the compressing and decompressing programs into the Nortons default directory. In this menu you can specify the method of compressing and encrypting of the compressed file with a password.

Auto menus: Switching on/off the display of the automatic menus. If switched on, the user defined menu will be active immediately after Norton Commander loaded. It is very comfortable for the less experienced user to configure the system in such a way that first you make the user menu with the more often used programs, switch on the automenu option and type the NC command line in the AUTOEXEC.BAT. P

Path prompt: Setting on/off showing of the active path in the DOS command prompt.

Key bar: Switching on/off the bottom menu.

Full screen: Showing the left and right window on the full screen or on the upper half of the screen.

Mini status: Setting the appearance of the detailed parameters of the files.

cLock: Switching on/off a clock in the upper right corner of the screen.

Save setup: Saving the configuration data. (This switch has no function if you switch on the auto setup option.)

NC stores the configuration data in a file called NC.INI (the user menu is stored in NC.MNU). Therefore if you started NC from a network server there will be problems with these files (e.g., the other network users can overwrite your NC.* files). Therefore it is worth to set up an environmental variable to determine the place of the initialization files. For this purpose you should add the following line to your AUTOEXEC.BAT:

SET NC=F:\PUBLIC\NC\MACHINE1 It tells to the Norton Commander that your files are in the directory given after the equation sign. The other terminals in the network may use the MACHINE2, MACHINE3, etc. directories. (Or you can specify any other directory also.)

Almost all the network programs use environment variables to store and retrieve the initial settings, screen types, printer drivers for the different terminals.

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1.5 Computer Networks

Classification of NetworksNetwork is a system of communication in which the computers connected onto the network can send and receive electronic information from each other regardless to their physical localization. Using simple data networks such as the telephone network, you can send messages in the form of sounds, texts and pictures, but you should organize the connections. The computer networks contain hardware and software equipments to manage the communication (bridges, routers, manager softwares, etc.). The end equipments are called terminals. There are central computers in several networks for public applications (host, server or mainframe machines).

We can classify networks considering physical localization of the stations as follows:

- local area networks (max. 5 km distance)- metropolitan networks (max. 25 km distance)- wide area networks (above 25 km distance).

In star networks the stations can communicate with each other through a central switch which can connect any station to an other one. This structure characterizes the simple data networks.

Structure of star networks

The hierarchical networks connect the stations to the equipments of a higher level. That is just like a tree. There is usually a mainframe in the root.

Structure of hierarchical networks

In the ring networks each station is connected only to its neighbours. If one of the terminals goes out of order, the network cannot work. (Therefore there is an other variation of it, where the connectors are outside the machines.)

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Architecture of ring networks

The most popular structure adopted in local area networks is the bus network. In these networks all the stations are connected to a bus thus all the messages appear in every station. Communication on the network is independent from the terminal, the only problem would be if the bus gets damaged.

Bus network

The data transfer rate of the networks can be measured by the number of signals transmitted per second. Its unit of measure is called baud. (Usually, 1 baud=1bit/sec).

The transmission can be synchronous when the same clock signal controls all the stations and it can be asynchronous when the pieces of the messages are sent in discretional moments. In this later case the stations should be signalled the beginning and end of data transmission.

The connection can be simplex (one way), half (semi) duplex (the two ways are alternate in time) or duplex (two directional in every time).

You can make, for example, a duplex connection between two IBM PCs through their serial ports with the so called handshake process. In this way there are separate wires for the signal ground, data transmission, ready to accept and end of transmission signals, and acknowledgment of receiving data. Thus you have to use 9 wires in a simple serial connection. The maximal transfer rate is 9600 baud, parity of the bytes can be checked or not, each byte can send information on 7 or 8 bits with 1 or 2 stop bits. You can set up the serial communication setup using DOS command MODE. For example,

MODE COM1:9600,N,8,1

means 9600 baud speed, no parity checking, bytes consisting of 8 bit information with 1 stop bit. This setting should be made on both of the computers after the physical connection was established. This is the simplest way to connect two computers. It is also possible to connect computers through the telephone network by using MODEMs (MODulator-DEModulator). The most popular MODEM is the acoustic coupler which should be connected to the serial port of the computer and then the telephone receiver should be placed on it.

Baseband networks can transfer only one package of information on a cable at the same time. Broadband networks can handle more than one package in a moment using of modulated sinus waves of different frequencies.

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The data transfer medium can be twisted pair of wires, coaxial cable, fiber optic cable or radio wave (microwave). Recently the fibre optic cables come into fashion because of their great advantages. For example, they can provide higher speed of communication and galvanic voltage differences never occur, therefore fiber optic cables are ideal to build a network of medium size. Smaller LANs (e.g., in a ward) still use "traditional" cables.

The communication can be realized through three main levels:

Organization of network communication

The lowest level is used to send, receive and check the signals. Transferring is managed on the middle level. The end-user contacts only with the highest level that gives advanced services (e.g., for file-handling). These three levels are divided into 7 further layers by the ISO standard (International Standard Organization).

The rules of information interchanging between these levels are prescribed in the so called protocols. These protocols are international standards.

Local Area NetworksTo fulfill the needs of wards and clinics of a hospital - which are in close vicinity to each other - the local area networks (LANs) offer the best solution. Its advantage is the possibility of communication between the terminals and the common usage of high capacity backing stores, printers or computers. Therefore the terminals can build up a common database. The local area networks can be connected to other LANs and they can reach national or international networks through special high distance communication networks. In the following we will introduce a few common LAN types.

ArcNet NetworkThe ArcNet is a baseband bus network with a data transmitting speed of 2.5 Mbaud. Its architecture is very interesting because it looks like a star network, since the terminals are connected to a central unit, the so called hub. However, this unit does not contain any switch. The information flowing in the network appears in all terminals but only the target computer can receive it. There are active hubs to connect 4, 8 or 12 terminals and the maximum number of the stations allowed is 255. "Active" means, that the unit not only distributes the signals, but it gains and reconstructs them, therefore a terminal can be located max. 650 m from the hub. There are also passive hubs (simple distributors) to connect 3 terminals that are close to each other (max. 30 m).

PCs can be connected to the network through an ArcNet-card inserted into one of their expansion slots. This card contains a BNC socket to which a 93 Ohm coaxial cable can be connected. There are also cards with two BNCs to form a small bus network of maximum 8 computers without any hub. In this case the computer should be connected to its neighbours. The 8 bit cards can be used in XTs and ATs, the 16 bit cards (which are faster) are applicable only for ATs. There is a dip switch on the card to set-up the identification number (node address) of the terminal in binary form.

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Architecture of ArcNet networks

Ethernet NetworkEthernet is also a baseband bus network. Its transfer rate is 10 Mbaud. The maximal length of a cable segment is 185 m (thin cable) but more segments can be connected via repeaters. The maximal number of stations is 1024. The medium can be twisted pair, thin coax, standard coax or fibre optic cable.

Architecture of Ethernet network

IBM PCs can be connected to the network via Ethernet-cards. These cards are more expensive than the ArcNet-cards but they are rather suitable for larger and faster networks. Nowadays Ethernet is the most often used network type to link IBM PCs or workstations.

The organization of message transfer is different in these two networks. The ArcNet network uses the token passing method: the right of sending a message goes round and round between the terminals. That is a time-consuming but powerful process. Ethernet manages the communication by collision detection. If two stations send message at the same time both of them must break it and then they begin it again after randomly selected delays. Therefore overtasking significantly reduces the effective transfer rate of the Ethernet networks. Because of this, if more than 16 terminals are connected to one network segment, the data transmitting speed reduces significantly. The 185 m limitation also can be described by the structure of the data transmitted. Each packet contains a header of fixed length. The length of this header is adjusted in such a way, that meanwhile the computer sends the last byte of the header, the first byte should reach the two ends of the segment. This overrides the possibility of data collision mentioned above and increases the speed of transmission.

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Linking Computer NetworksAs we said, the segments of a local area network can be linked with repeaters (or with hubs). In this case the messages of the terminals appear in all of the segments (but only the target computer can receive and decode it).

If you use bridges between the segments, the signals will go through the bridge if the target station can be fond in the other side of the bridge. This method reduces the chance of overloading. The bridge can be managed locally or by a remote manger computer. Management means that you can program the traffic control functions of the bridge. For example, you determine what terminals may access others. Therefore bridges make the transfer speed faster and provide shelter from illegal intruders.

Routers have more functions than bridges. They can optimize the paths of the information in sophisticated networks. They can find all the different paths for sending information from a unit to an other. They can choose the optimum path or choose another one, if any part of the cabling is damaged.

Gateways are used to connect different types of networks. They are special computers with a program which can transform the protocols of the two networks. Modern network operating systems offer built-in software gateways by developing common communication protocols (ISO standards).

Large networks need a high capacity host computer to store, organize and forward the messages and to offer such services as time-sharing and multitasking. Formerly the VAX minicomputers produced by the DEC (Digital Equipment Corp.) and the IBM mainframes were the most often used hosts. Recently the so called workstations are in general use in distributed networks (where more than one host can be found). These machines have 1-4 microprocessors of high capacity (SPARC, RISC), 32-128 Mbyte RAM, 1-3 Gbyte hard disk and magnetic tape unit, CD-ROM. They use the UNIX operating system.

Today's best network system is the FDDI (Fibre Distributed Data Interface) which can be used in metropolitan networks. For example, the urban network of the University of Debrecen (which is under construction) will be an FDDI main ring established between the institutions. The Ethernet system LANs of the colleges and universities will be connected to this main ring through routers.

The LAN of the University Medical School will be an Ethernet ring. The "ring" means that the two ends of the main segment will be connected to each other through a bridge which will close the circuit if any breakdown occurs. This main ring can be easily reshaped into an FDDI system later. The LANs of the departments will be connected to the main ring directly or through routers.

The wide area networks are provided by common carrier companies. The terminals can join these public networks through an X.25 interface which is in general use. The transmission method of the public packet networks is the so called packet switching which means that the messages are divided into packets of equal lengths and these packets are stored and sent through the nodes of the network to the destination station. Today the transfer rate is only 9600 baud, but 64 kbaud and 1 Mbaud systems are under construction.

One of the most important services of the public packet networks is the electronic male (e-mail). Every end-user has an electronic mail box that can receive or send text files, programs, pictures, sound files, etc. from or to other boxes. Our national e-mail system (ELLA) is able to contact with the large international networks such as INTERNET or BITNET. There are closed networks that use the public network services but they cannot be reached by unauthorized stations (e.g., the academic network of Europe, the so called EARN).

NOVELL NetwareThe existing LANs of our university consist of IBM XTs and ATs as terminals, AT 386 and 486 machines with a large hard disk as servers. They are either ArcNet and Ethernet networks. There is a long ArcNet backbone to link the LANs of the clinics. Our computer lab is similar to a clinical

35

network. Nevertheless, clinical networks contain more machines, servers, safety backup stores (streamers, magneto-optical or optical devices). Novell can use either ArcNet or Ethernet network elements. It provides a so called internal bridge which joins an ArcNet and an Ethernet network at the same time.

The Novell Netware (network operating system) is installed on the hard disk of the server machine. The terminals use the MS-DOS operating system which is placed on their boot floppy disk, hard disk or in a special boot EPROM. After booting, two resident programs should be evoked (IPX.COM and NETX.COM). IPX.COM contains the network communication protocol meanwhile the NETX.COM establishes the logical connection between the terminal and the server. If you put a system floppy disk into the A: drive with these files and the following AUTOEXEC.BAT, the terminal will be attached to the network automatically:

IPXNETXF:LOGIN

Then you can use your local disk drives as usual with the A:,... E: identifiers. The most important service of the netware is to provide further disk drives (starting from F:) for the terminals with F (or higher) identifier. This disk can be used in common with all the terminals. The user can attach to the network with the LOGIN program and leave it with the LOGOUT. The administrator of the system is the supervisor who controls the rights of the other users with the SYSCON program. The supervisor binds a login name and a password to the users or group of them and he gives the rights to the users in every directory. These rights can be the follows:

R: Read from files.W: Write to files.O: Open existing files.C: Create new files, make new subdirectories.D: Delete existing files and erase existing subdirectories.P: Change users' directory rights.S: Search the directory.M: Modify file status flags.P: Parental rights (only for directories)Su: Supervisory rights (only for directories)

For example, the students can use our network with the "student" login name without any password. In general, a password is required which should be touch-typed because it does not appear on the screen.

If you make any mistake the netware will send the message Access denied, and you will not be attached to the network. In this case you may only use the local peripherals or you can retry attaching by typing the LOGIN command.

The hard disk F: looks just like a local one. The programs are placed in directories and the usage is similar as with a local winchester. But there is a problem in file-handling: if two terminals try to write into the same file at the same moment the system will be frozen. Therefore the application programs must protect their work files from the simultaneous writing. There are a few special directories on the disk:

DOS: contains the COMMAND.COM and the external DOS-commands.LOGIN: contains the LOGIN and LOGOUT programs.MAIL: mail-boxes for the users' messages.

PUBLIC: service programs and network commands.SYSTEM: service programs and system generator files.

The end-users may use either their own local printer or the network printers connected to the server. The supervisor can create printing formats and queues for the printers with the PRINTCON and PRINTDEF programs. The queue is series of files on the hard disk of the server waiting for printing in a priority order. The users can send files to print on a central printer by using the following command:

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NPRINT "file-name" Qqueue-name(e.g., NPRINT "lectnote.txt" QQ0).

The local printer port also can be re-routed to the central printer. In this case all the printing signals will be transferred to the central printer instead of the local printer. The command is as follows:

CAPTURE Q="queue-name" (e.g., CAPTURE Q=Q0)

The local printer will be accessible only after typing in the ENDCAP command.

The terminals can send messages to each other with the SEND command:

SEND "message" TO STATION station number or login name(e.g., SEND "Hello!" TO STATION 1).

The number of the station is not bound to the machine, it depends on the order of login in.

If there are different servers in a large network (e.g., the DOTE LAN where almost every department has a Novell server) you can get the list of the active servers by typing the SLIST command in. If you have access rights on an other server you can access it with the LOGIN “servername”/”username” command. For example, from an othe department you can use our server after the following command:

LOGIN ofk/student

UNIX Operating SystemThe UNIX operating system came out about 20 years ago. In our country it begins to spread only recently because of the former COCOM prohibitions and the low capacity of our machines.

The UNIX has many similar features with MS-DOS. However the concepts of this operating system are something new: this is a multi-tasking and multi-user system. The file handling features are common in both network systems. The most important difference between these networks is, that the UNIX can run more than one job at the same time. Further similarity is that the UNIX gives also an unfriendly, prompt- and character oriented user interface. In recent times you can use menu controlled shells in UNIX (like the DOSSHELL or the Norton Commander on an MS-DOS machine) and there is a new popular graphic interface the X-WINDOW (corresponding to Microsoft Windows).

The IBM PCs can create a UNIX partition on their hard disk but the UNIX needs larger backing store and memory capacity than MS-DOS. Therefore IBM PCs are not really suitable to use as a stand-alone UNIX station. But if you connect your S-VGA 386 or 486 PC to a UNIX workstation through the serial port or via an Ethernet network and load a terminal emulator software you will get an inexpensive UNIX graphic terminal. In this case you can use your terminal also as an MS-DOS machine with your well-known applications.

The simplest UNIX terminals contain only an alphanumeric display unit and a keyboard. These terminals are controlled by the terminal controller card built into the server machine. The recently used terminals contains a microprocessor and 4-8 Mbyte of RAM. The so called X-terminals produce high quality graphics, for example, 1024x1280 pixel and 256 colours.

UNIX is a much more powerful network operating system than NOVELL. The reason for this is that NOVELL always loads the programs and data into the memory of the terminal first, and then the programs run on the terminal. This is very time-consuming, and it involves the risk of damaging data while transferring. Whereas, UNIX runs the programs in the server machine, the terminal sends only a few bytes to ask for starting a job and then gets back only the results. This method is very fast and there is no risk of any damage of data.

The UNIX uses the so called IP protocol (=Ethernet_II communication standard) of the Ethernet system which is in general use in the computer networks. Novell uses the IPX protocol of Ethernet (=803.2 communication standard).The former versions of NOVELL (2.xx) were not compatible with

37

this protocol but the new generation (3.1, 3.2) can communicate with the UNIX machines through an Ethernet card placed into the NOVELL server.

38

1.6 Dictionary

Aabandon felad, abbahagyabort megszakítabsolute abszolútAC (Alternating Current) váltóáramaccept elfogadaccess hozzáférés, bemenetaccess time hozzáférési idôaccount számla, elszámolaccounting könyvelés, elszámolásaccumulator akkumulátor(regiszter)acknowledgement elismerés,

beismerés, köszönetnyílvánításacoustic akusztikaiacoustic coupler akusztikus csatolóactivate aktivál, aktivizálAD-converter analóg-digitális

átalakítóadaptive adaptívadd összead, hozzáadadder összeadóaddition összeadásaddress cím, címzésaddress bus címbuszadjustment kigazításadvanced haladó, fejlettaggregate összes, összeg, összegezaggregating összegzésAI (Artificial Intelligence)

mesterséges intelligenciaALGOL (ALGOrithmic Language)

programozási nyelv nevealgorithm algoritmusalign sorba állít, egyenesbe hoz (pl.

margót)alignment sorba állítás,

sorkiegyenlítésall minden, mindegyikallocation kiosztás, elhelyezésalpha alfaalphanumeric alfanumerikusalt (alternate) váltóALU (Arithmetic and Logic Unit)

aritmetikai és logikai egységanalog analóganalyser analizátor, elemzôand és, logikai ésannotate jegyzetekkel ellátannotation megjegyzés, magyarázatANSI (American National

Standards Institute) Amerikai Szabványügyi Hivatal

APL (A Programming Language) programozási nyelv neve

append mellékel, hozzáfuz (pl. rekordot)

APPLE (Apple Computer Inc.) számítógépgyártó cég

application alkalmazás, használatapplication package alkalmazói

programcsomag, felhasználói programcsomag

application software alkalmazói program, felhasználói program

arc ívarchitecture felépítés, architektúraarchive archívarea terület, felület, felszínargument argumentum, független

változóarray tömb, mátrix, elrendezésarrow key nyilas (kuzorvezérlô)

billentyuartificial intelligence mesterséges

intelligenciaASCII (American Standard Code

for Information Interchange) karakterek szabványos kódrendszere

assembler assembler fordítóprogramassembly programozási nyelvassist kisegít, támogatasynchronous aszinkronAT (Advanced Technology) IBM

személyi számítógép típusattach hozzácsatolattribute jellemzô, attribútumaverage átlagaxis tengely (koordináta rendszerben)

Bbacking store háttértárbackslash fordított per jel (\)backspace visszaléptetés,

visszatörlés (karakter, billentyu)backtrack visszalépbacktracking visszalépéses keresésbackup tartalék (erôforrás, másolat),

biztonsági (erôforrás, másolat), biztonsági másolatot készít

bad rosszband sávbanner fejléc, címfejbar vonal, korlát, rúd, oszlopdiagram

39

bar code vonalkódbase alap, bázisbaseband alapsáv, alapsávúbaseband network alapsávú hálózatBASIC (Beginners' All-purpose

Symbolic Instruction Code) programozási nyelv neve

bat batch-file kiterjesztésebatch kötegbatch-file kötegelt feldolgozást leíró

állománybatch-processing kötegelt

feldolgozásbaud adatátviteli sebesség

mértékegysége (bit/sec)BCD (Binary Coded Decimal)

binárisan kódolt decimális számábrázolás

begin elkezd, elkezdôdikbell csengô, hangjelzésbenchmark program tesztprogrambetween közöttbinary bináris, kettes

számrendszerbeli, kétértékubinary tree bináris faBIOS (Basic Input-Output System)

alap bemeneti-kimeneti rendszerbit (Binary digIT) bináris számjegy,

tárolóhely egy számjegy számárabit image bittérképépes képbit map bittérképblank üresblink villogásblock blokkblock diagram blokkdiagramBMDP (BioMeDical Computer

Programs) orvosi statisztikai programcsomag

board áramköri lapbold kövér karakterboolean logikaiBoolean algebra Boole-algebra,

logikai algebraboot, bootstrap betöltô (a.m.

csizmahúzó)border keret, szegély, határboth mindkettôbottom vége, alja vminekbox keretezô négyszögbracket zárójelbranch elágazásbreak szünet, töréspont, félbeszakításbridge hídbroadband szélessávúbroadband network szélessávú

hálózatbroadcast adás, üzenetközvetítés,

musorszórás

browse átnézés, böngészés, olvasgatás

bubble jet printer buboréksugaras nyomtató

bubble memory buborékmemóriabubble sorting buborék rendezésbuffer átmeneti tárolóbug programhiba (a.m. bogár,

poloska)bullet golyóbus busz, sínbus terminator buszlezáró,

kábelzáróbusbar buszvonal, sínvonalbypass összekötô út, kitérô

Ccable kábelcache memory gyorsító tárCAD (Computer Aided Design)

számítógéppel támogatott tervezés

CAI (Computer Assisted Instruction) számítógépes oktatás

CAL (Computer Assisted Learning) számítógépes tanulás

calculator számológép, kalkulátorCALL (Computer Assisted

Language Learning) számítógépes nyelvtanulás

CAM (Computer Aided Manufacturing) számítógéppel támogatott gyártás

cancel érvénytelenít, visszavoncapacity kapacitás, (adat)befogadó

képességcapital nagybetucapstan görgô, dobcapture begyujtés, elfogáscard kártyacarriage return kocsi vissza (sorvég)

jelzô karaktercarrier vivô, vivôfrekvenciacarry átvitelcarry flag átvitel jelzô bitcartridge kazetta (mágnesszalag, -

lemez, nyomtatószalag stb.)case eset, állapot, tokcassette kazettacatalogue katalógusCD-ROM (Compact Disc Read Only

Memory) otikai lemezes tárolócell cella, sejtcenter középpont, középre igazít

(szöveget)centered középre igazított (szöveg)

40

CGA (Color Graphics Adaptor) színes grafikus kártya

chain lánc, láncoláschange változtatáschannel csatornacharacter karaktercharacter generator

karaktergenerátorcharacter recognition

karakterfelismeréscharacter set karakterkészletchart grafikon, táblázatcheck ellenôrzéschecksum ellenôrzô összegchi-squared distribution khi-

négyzet eloszláschip integrált áramköri lapkachoice választás, választékchoose választ, kiválasztcircle kör, körforgás, körbemegycircuit áramkör, körforgás, kerületcircuit board áramköri lapclause mellékmondatclear törölclick kettyenés (billentyuzet),

kattintás (egér)clipboard kapcsolótáblaClipper adatbáziskezelô nyelv

(fordítóprogram) (a.m. remek dolog)

clock signal órajelclose lezárcluster fürt(elemzés)CMI (Computer Managed

Instruction) számítógéppel irányított oktatás

co-processor koprocesszor, segédprocesszor

COBOL (COmmon Business-Oriented Language) programnyelv elnevezése

code kódcoding kódoláscolon kettôspontcolor színcolumn oszlop, hasábcolumnwise oszlopfolytonosancom (command) parancsállomány

kiterjesztésecombine egyesít, vegyít, kombinálcomma vesszôcommand parancs, utasításcommand line parancssorcomment megjegyzéscommon közöscompact kompakt, összetömörítettcompare összehasonlítcompatible kompatibilis,

összeegyeztethetô

compile kompilál, lefordít, összeszerkeszt

compiler fordítóprogram, szerkesztôprogram

completion befejezéscomponent komponens, alkotórészcompose összeállít, összeszedcompute kiszámítcomputer számítógépcondensed összenyomott karaktercondition feltételconditional feltételesconfiguration konfiguráció, alakzat,

összeállításconfirm megerôsít, bizonyít, hitelesítconsole kezelôpultconstant konstans, állandócontain tartalmaz, magában foglalcontent tartalom, terjedelem,

befogadóképességcontinous folyamatoscontinue folytatcontrol vezérel, ellenôriz, felügyelcontrol unit vezérlô egységcontroller vezérlô, ellenôrzôconvert konvertál, átalakítconverter konverter, átalakítócoordinate koordinátacopy másolat, lemásol, másolcore mag, központi részcorner sarokcount számolás, számolcounter számláló, számoló,

számológépcourir kurir betutípuscpi (character per inch) nyomtatási

karaktersuruség mértékegységeCPU (Central Processing Unit)

központi egységcreate létrehozcriterion feltétel (tbsz. criteria)CT (Computer Tomograph)

számítógépes rétegvizsgálóctrl (control) kontrol váltóbillentyucurrency pénzforgalom, valutacurrent áram, irány, aktuáliscursor kurzorcurve görbe, görbület, függvényábracut sheet feeder lapadagoló

(printerhez)cycle kör, sorozat, cikluscylinder henger, dob

Ddaisywheel printer

margarétatárcsás printerdata (tbsz.) adatok

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data analysis adatelemzésdata bus adatbusz, adatsíndata management adatkezelésdata processing adatfeldolgozásdatabase adatbázisdatabase language adatbázis kezelô

nyelvdate dátumdatum (tbsz.: data) adat, adottságDC (Direct Current) egyenáramDD (double density) dupla

írássuruségu mágneslemezdebugger hibakeresô (program)debugging hibakeresésDEC (Digital Equipment Corp.)

számítógépgyártó cégdecimal decimális, tízes

számrendszerbeli, tizedesjegydecision döntésdeclaration meghatározás (típus,

eljárás stb.), deklarációdecoder dekódolódecrease csökkentdecryption titkosítás visszaalakításadefault alapértelmezésdegree of freedom szabadsági fokdel (delete) töröldelay késleltetésdelete töröldelimited elhatároltdelimited file határolójelekkel

elválasztott mezôkbôl álló szöveges állomány

delimiter határolójeldensity suruség, denzitásdeny tagad, megtagaddepend függdependent függôdescription leírásdescriptor line leíró sordesktop publishing

kiadványszerkesztésdestination célstation, rendeltetési

helydestroy megsemmisítdeviation szórás, eltérésdevice eszköz, szerkezet, készülékdevice driver berendezésvezérlôdiagnose diagnosztizál, hibát keresdiagnostic diagnosztikusdiagnostic routine hibakeresô

eljárásdigital digitálisdigitizer digitalizálódigitizing pad digitalizáló tábladiode diódadir (directory)direct access közvetlen hozzáférés

directory katalógus, címjegyzék, könyvtár

disable letilt, megtiltdisassembler gépi kódot assembly

nyelvre visszafordító programdisc, disk, diskette lemezdiskcopy lemezmásolatdisplay kijelzô, display, monitordistribution eloszlásdivide osztdivision osztásDMA (Direct Memory Acces)

közvetlen memóriahozzáférésdoc (doceumentation)

programleírás, dokumentációdomain tartomány, terület, mágneses

doménDOS (Disk Operating System)

lemezes operációs rendszer (IBM)dot pont, pontozdot matrix printer mátrixnyomtatódouble dupladouble spacing dupla (2-es)

sortávolság (gépírásnál)down lefelédownload áttöltésdpi (dot per inch) felbontás

mértékegysége nyomtatóknáldraft vázlat, durva karakterképdrag behúz, vonszol, magával viszdraw rajzoldrill gyakorlásdrive meghajtó, hajtómu,

lemezegységdrum dobDS (Double Sided) kétoldalas

mágneslemezDTP (DeskTop Publishing)

kiadványszerkesztésdump tárkiírásduplex duplex, kétszeresdynamic dinamikus, változódynamic memory dinamikus

memória (pl. RAM)

Eeach mindegyikecho visszajelzésedge széle vminekeditor szerkesztôeffect hatásEGA (Enhanced Graphics Adaptor)

grafikus kártya típuseject lapdobás (nyomtatón), kidob

(lapot)elapsed time elhasznált idô, eltelt

idô

42

electric elektromoselectronic elektronikuselectronic circuit elektronikus

áramkörelectronic mail elektronikus

levelezés, elektronikus postaelement elemelse egyébként, máskülönbenempty üresEMS (Extended Memory System)

kiterjesztett memória kezelôemulation emulációenable felhatalmaz, engedélyezencode kódolencoding kódolásencryption titkosítási kódolásend végenhanced kiemelt, fokozott,

megnagyobbítottenhancement fokozás, kiterjesztés,

megnagyobbításenter beír (pl. parancsot), beléptet,

beadentire egész, teljesentry beírás, beléptetés, beadás,

beadott adat, tétel, belépésenvironment környezetEOF (End Of File) file vége mutatóEOLN (End Of LiNe) sor vége mutatóEPROM (Erasable Programmable

Read Only Memory) törölhetô-programozható olvasható memória

equal egyenlôequipment berendezésequivalence egyenlôség,

ekvivalenciaerase törölerror hibaerror message hibaüzenetescape (esc) kiszökik, kilépeven number páros számexact pontos, egzaktexclusive kizáróexe (executable) végrehajtható

állomány kiterjesztéseexecute végrehajtexist létezikexpanded memory kiterjesztett

memoriaexpansion slot bôvítési hely/résexpert system szakértô(i) rendszerexpertise szakértelemexplore felderít, kutatexponential exponenciálisexport adatkivitelexpose bemutatexpression kifejezésextend kiterjeszt

extended memory kiterjesztett memória

extension kiterjesztésextern, external külsôextra extra, külön, rendkívüliextract kiemel, kivon

Ffacsimile fakszimile, hasonmás,

grafikát továbbító rendszer, (tele)fax

fail elmulaszt, elvét, megbukikfailure hiba, sikertelenség, bukásfalse hamis, logikai 0FAT (File Allocation Table) file

helyfoglalási táblázatfeature tulajdonság, jellemzôfeed töltés, befuzés (pl papír befuzése

a nyomtatóba)feedback visszacsatolásfibre optics száloptikafield mezôfile file, állomány, fájlfile management file-kezelés,

állománykezelésfile manager file-kezelô,

állománykezelôfilename file-név, állománynévfill feltölt, betölt, megtöltfilter szur, szurôfinancial pénzügyifind talál, megtalál, megkeresfit illeszt, egyeztetfix rögzítfixed állandó, rögzített, merevfixed disk merevlemez, winchesterfixed point fixpont, rögzített pontflag jelzô, jelzôbitfloat lebeg, úszikfloating point notation

lebegôpontos számábrázolásfloppy hajlékony, lazafloppy disk hajlékony mágneslemezfloppy disk drive hajlékony lemez

meghajtóflops (Floating Point Operations

Per Second) másodpercenkénti lebegôpontos muveletek

flow folyamatflow chart folyamatábraflow-control folyamatszabályozás,

adatáramlás vezérlésfont betukészletfooter, footnote lábjegyzetform lap (nyomtatópapír)form feed laptovábbítás (lap végére)

43

format formátum, formattálás, lapelrendezés

formula képletFORTRAN (FORmula TRANslater)

programozási nyelv neveframe keret, lap, cetlifreeze befagyasztfrequency frekvencia, gyakoriságfrequency distribution gyakorisági

eloszlásfull tele, teljesfunction függvény, funkció, muködésfunction key funkció billentyufunctional language függvényalapú

programozási nyelvfuse biztosíték

Ggame theory játékelméletgarbage szemét, hulladék, értéktelen

információgarbage collection szemétgyujtés,

értéktelen információk kiszurésegate kapu, logikai kapu, kapuáramkörgateway átjárógeneral általánosget kap, vesz, betöltglobal globális, teljesglossary szógyujteménygo megy, indulgoal célgothic gótikus (karakterkészlet)goto statement vezérlésátadó

utasításgraph grafikon, diagramgraphic grafikusgraphic mode grafikus üzemmódgraphics card grafikus kártyagray scale szürkeskálagrid rács, rácsozgroup csoport

Hhack feltör (programot, rendszert)hacker feltörô (számítógépes betörô)half félhalt megállás, leállításhandle kezel, irányíthandler kezelô, irányítóhandshake kézfogáshandy scanner kézi képdigitalizálóhard disk merevlemez, winchesterhard disk drive merevlemez

meghajtóhardcopy papírmásolat képernyôrôl

hardware hardverhardwired huzalozotthazard kockázat, veszélyHD (High Density) nagy

írássuruségu (1,2 Mbyte-os) mágneslemez

HDD (hard disk drive) merevlemez egység, winchester

head fejheader fejlécheap halom(tár)height magassághelp segítséghexadecimal tizenhatos

számrendszerbelihi (HIgh) felsô (byte)hidden rejtetthidden file rejtett filehigh magashigh resolution nagyfelbontásúhigh-level programming language

magasszintu programozási nyelvhighlight kiemelt rész kivilágított rész histogram hisztogramhit leüt (billentyut)home alaphelyzethome computer házi számítógéphorizontal vízszinteshost computer gazda számítógéphub csillagcsatolóhuge óriási

II/O (Input/Output) bemeneti-

kimenetiIBM (International Business

Machines) számítógépgyártó cégIC (Integrated Circuit) integrált

áramköricon ikon, kép, piktogramidentification azonosításidentifier azonosítóidentify azonosítif statement feltételes szerkezetignore figyelmen kívül hagy nem

vesz tudomásul, mellôz image képimage processing képfeldolgozásimpact printer érintéses nyomtatóimport adatbehozatalincorrect hibás, helytelenincrease megnövel, fokoz, szaporítincrement növekedésindent bekezdésindex index, mutatóindex file index állomány, index fileindex register indexregiszter

44

indexed addressing idexelt címzésindexed file indexelt állomány,

indexelt fileindexed sequential file

idexszekvenciális állomány, indexszekvenciális file

indicator jelzôindirect addressing indirekt címzésinformation információinformation technology

információtechnológiainitialization inicializálás,

kezdôadatok beállításainitialize inicializálink jet printer tintasugaras

nyomtatóinput bevitelinput device beviteli eszközinput-output beviteli-kiviteliins (insert) inzert, beszúrásinstall installál, üzembe helyezinstallation installáció,

üzembehelyezésinstruction utasítás, parancs,

értesítés, oktatásinstrument eszközinteger egészintegrated circuit integrált áramkörintensity intezitásinteractive interaktív, párbeszédesintercept metszéspontinterface interfész, csatlakozási

felületinternal belsôinternational nemzetköziinterpreter értelmezôinterrupt megszakításinterrupt handler

megszakításkezelôinterrupt request megszakításkérésinterrupt vector megszakítás vektorintroduction bevezetésinverse inverzIRQ (Interrupt ReQuest)

mregszakításkérésISO (International Organization

for Standardization) Nemzetközi Szabványügyi Szervezet

IT (Information Technology) információtechnológia

italic dôlt betu, kurzív szedésitem tétel, cikkiteration iteráció

Jjob munka

join illeszt, érintkezik, kapcsolódikjoystick botkormányjump ugrikjump instruction ugró utasításjumper átkötésjunction érintkezés, átmenet,

érintkezési felületjustification sorkizárás,

sorkiegyenlítésjustify kizár (sort), kiegyenlítjustyfied kizárt, kiegyenlítettKK kbytekey kulcs, billentyu, gombkeyboard billentyuzetkeypad billentyuzet (kisméretu)keyword kulcsszó, fenntartott szókill kiirtás, megsemmisítés,

hatástalanításknowledge tudásknowledge base tudás alapú

Llabel címkeLAN (Local Area Network) lokális

hálózatlandscape: fekvô formátumú kép

("tájkép")laptop hordozható számítógéplarge nagylarger than nagyobb mintlaser printer lézer nyomtató,

elektrofotografikus nyomtatólatch reteszlayout tervrajz, alaprajz, elrendezésleave elhagy, kilépLED (Light Emitting Diode)

fényemittáló diódaleft bal, baoldal, baloldalra esô részlegend felirat, címszöveglength hosszúságless than kevesebb mintletter quality levélminôségu

nyomtatáslevel szint, színvonallibrary könyvtár, programkönyvtárlight pen fényceruzaline vonal, sorline feed sortovábbításline printer sornyomtatólinedraw vonalrajzoláslink lánc, láncol, kapcsolat, kapcsollink editor szerkesztô-összekapcsoló

programlinker összekapcsoló program

45

LISP (LISt Processing) programozási nyelv neve

list lista, listázlo (LOw) alsó byteload betölt, töltlocal helyilocal area network helyi számítógép

hálózat, lokális hálózatlocate elhelyez, helyet megállapítlocation elhelyezkedéslock zár, zárollogarithm logaritmuslogaritmic logartimikuslogical function logikai függvénylogical operation logikai muveletlogical programming laguage

logikai programozási nyelvlogin bejelentkezés, belépéslogout kijelentkezés, kilépéslook up kereslow alacsonylow-level programming language

alacsony szintu programozási nyelv

lowcase, lower case kisbetusLQ (Letter Quality) levélminôséguLSI (Large Scale of Integration)

nagyfokú integráció

MM Mbytemachine code gépikódmacro makroutasításmacro assembler makroutasításos

assemblermagnetic mágnesesmagnetic card mágneskártyamagnetic tape mágnesszalagmail postamailbox postaláda, elektronikus

levelezés tárterületemailmerge körlevél készítésmain fômain memory központi tármain program fôprogrammain storage, main store központi

tármainframe nagyszámítógép,

nagyszámítógép központi egysége, nagyszámítógépes rendszer

maintenance karbantartásmanage kezel, vezet, végrehajt, intézmanager kezelô, vezetô, végrehajtó,

intézômanual kézikönyv, kezelési útmutató,

manuális

map térkép, tervrajzmargin margómark jel, jelöl, megjelöl, kijelölmaskable interrupt maszkolható

megszakításmatch egyezés, illeszkedés, egyeztet,

ösz-szeillesztmatrix printer mátrixnyomtatómaximal maximálismean jelentés, középérték, átlagmeasure méret, mérték, mérmeasurement mérésmemory memóriamenu menü, étlapmenu-driven menüvezéreltmessage üzenetMGP (Monochrom Graphics

Adaptor) monokróm grafikus kártya

microcomputer mikroszámítógépmicropocessor mikroprocesszorminicomputer miniszámítógépminimal minimálismnemonic emlékezteterôsítômode módMODEM (MOdulator DEModulator)

telefonos adatátvivô eszközmodification módosítás,

meghatározás, változtatás, mérséklés

modify módosít, meghatároz, mérsékel

modular programming moduláris programozás

modulo operation modulusképzés, maradékos osztás

monitor monitor, képernyôs megjelenítô, felügyelô program

monitorizing monitorozás, felügyelésmonochrom monokrómmother board alaplapmouse egérmove mozgat, elmozgatmulti-tasking egyideju végrehajtás,

párhuzamos végrehajtásmulti-user system többfelhasználós

rendszermultiplexer adatbegyujtômultiplication szorzásmultiply szorozmultiprogramming

multiprogramozásmute elnémít

Nname névnatural természetes

46

natural language természetes nyelvnatural language interface

természetes nyelvi interfacenear letter quality közel

levélminôségu (nyomtatás)negate tagadnegation tagadás, negációnest beágyazásnetware hálózati operációs rendszer

(NOVELL)network hálózatnew újnext következôNeXT nagyteljesítményu

mikroszámítógép típusNLQ (Near Letter Quality) közel

levélminôségu (nyomtatás)No. sorszámnode csomópontcsúcsnotebook kisméretu személyi

számítógépnon-impact printer nem érintéses

nyomtatónon-maskable interrupt

nemmaszkolható megszakításnone egyik semnor kizáró vagynormal normálisnot nem, logikai nemnumber számnumeric numerikus, számjegyesnumeric processor numerikus

processzor, ko-processzor, segédprocesszor

Oobject cél, tárgy, témaobject code célkódobject-oriented programming

objektum orientált programozásodd number páratlan számoff-line kikapcsolt, lekapcsoltold régiomit elhagy, elmulaszt, kihagy,

kifelejton-line bekapcsolt, rákapcsoltopen nyitott, nyit, megnyitoperating system operációs

rendszeroperation muveletoptical optikaioptical disk optikai lemezoptical storage optikai tárolóoption opció, választási lehetôségoptional opcionális, választhatóor vagy, logikai vagyorder sorrend, rendez

ordering rendezés, sorbaállításorganize szervezOS (Operating System) operációs

rendeszerother egyéboutline vázlat, kivonat, körvonaloutput kimenetoverflow túlcsordulásoverlap átlapolás, többszörör

muveletvégrehajtás, párhuzamos muveletvégrehajtás

overlay átfedés, többszörös memóriakihasználás

overwrite felülír

Ppack tömörítpacked tömörítettpage lap, oldalpage number oldalszám, lapszámpaired párospaired t-probe egymintás t-próba palmtop egészen kisméretu PCpan pásztázpanel panel, áramköri lap,

kapcsolótáblaparagraph paragrafus, bekezdés,

szakaszparallel párhuzamosparallel port párhuzamos portparameter paraméter, segédváltozópark parkolparser mondatelemzôparsing mondatelemzéspass átfutás, átmenet, átvizsgálás,

levizsgáláspassword jelszópath út, útvonal, elérési útpathway út, útvonalpattern mintázat, alakzatpattern recognition alakfelismeréspause szünetPC (Personal Computer) személyi

számítógéppeek memóriatartalom kiolvasásapercent százalékperipheral periféria, perifériálispersonal computer személyi

számítógéppica ciceró betupicture képpicture processing képfeldolgozáspie kördiagrampin tu, érintkezôpipeline csôvezeték, adatcsatornapitch osztásköz, suruségpixel képpont

47

placement elhelyezésplotter rajzgépplug dugasz, csatlakozópoint pontpointer mutatópoke memóriatartalom beírásapolygon sokszögpolyline sokszögvonalpop lekap, veremtárból kiveszport bemeneti-kimeneti kapu,

perifériaillesztôportable hordozható, átvihetô,

gépfüggetlenportrait: álló formátumú ("portré")

képposition helyzet, helyi érték,

pozocionálpotential potenciál, lehetôségpower energia, meghajtás, hatványpower supply energiaellátásprecision pontosságpredicate predikátum, állítás,

kijelentéspress nyom, lenyomprevious elôzôprimary elsôdleges, fôprimary storage fôtárprint nyomtat, printelprinted circuit nyomtatott áramkörprinter nyomtatópriority prioritásprobability valószínuségprobably valószínulegprocedure eljárás, procedúraprocess folyamat, eljárás, feldolgozprocessing feldolgozásprofessional szakmai, szakértôiprogram counter programszámlálóprogrammer programozóprogramming language

programozási nyelvPROLOG (PROgramming in LOGic)

logikai programozási nyelv neveprompt parancsbeírási hely,

készenléti üzenetproof biztos, ellenállóproper valódi, igazi, megfelelôproportional aránylagosprotect védprotection védelemprotocol protokoll, eljárásszabályzatPS (Personal System) IBM személyi

számítógép-családpseudocode pszeudokódpublic közös, nyilvánospulse impulzuspunched card lyukkártyapush nyom, benyom, veremtárba

helyez

put tesz, helyez

Qquality minôségquery kérdésqueue sor, várakozási lista, sorba állquick reference gyors referenciaquit kilép

RRAM (Random Access Memory)

véletelen hozzáférésu tároló, tetszôleges hozzáférésu tároló

random véletlen, véletlenszerurange tartomány, kiterjedés,

értékkészletrank rangrank correlation rangkorrelációraster raszterraster scanning raszter pásztázásrate ráta, arány, mértékread olvas, beolvasread-only csak olvashatóready készreal number valós számreal-time valós idejurecall visszahívreceive vesz, kap, kézhez kaprecognize felismerrecord rekordrecover helyrehoz, helyreállítreference referencia, hivatkozás,

tájékozatatásreformat újraformátumozásregister regiszterregression regressziórelation reláció, kapcsolatrelational database relációs

adatbázisrelay relé, közvetítôrelease felszabadít, kikapcsol,

megengedrem (remark) megjegyzésremote távoliremove eltávolítrename átnevezrepaginate újrasorszámoz (lapokat)repeat ismételrepeater jelismétlô csatolórepetition ismétlésreplace helyettesítreplicate másolatot készítreport jelentrequest kérésreset újraindít, alaphelyzetbe hoz

48

resident rezidens, tárban maradóresolution felbontás, megoldás,

képfelbontásrest maradék, maradvány, hátralevôrestore helyreállít, visszaállít, újra

berakrestrict korlátoz, megszorítretrieve betölt, visszatölt,

visszaszerezretry újra megpróbálreturn visszatérreverse ellekezôje, fordítottja,

ellenkezôjére változtat, visszafordít

ribbon szalag, írószalag, printer szalag

right jobb, jobboldali, jobboldali maradék

ring gyururing network gyuruhálózatrise emelkedikrisk veszélyROM (Read Only Memory) csak

olvasható memóriaroman antikva betutípusroom hely, térroot gyökér, fastruktúra kindulópontjaround kerekítroute útvonalroutin rutinrouter útvonalválasztó csatolórouting útvonalválasztás,

üzenetküldés, irányításrow sorrowwise sorfolytonosruler vonalzórun fut, programindításrunning programfutásrunning head futófejlécruntime futási idôbeli, futási idôruntime error futási programhiba

Ssafe biztos, veszélytelen, biztonságossafety biztonságsame ugyanazsample példa, mintasampling mintavételezéssave mentés, kimentésscale skálascanner pásztázó, letapogató,

képdigitalizáló készülék, lexikai elemzô, átolvasó

scientific tudományosscientific notation exponenciális

számábrázolás

scope érvényességi terület, hatáskör, kiterjedés

scrap hulladékscreen képernyô, szurôscript kézirás, kéziratscroll képernyôgörgetésSD (Single Density) egyszeres

írássuruségu mágneslemesSD (Standard Deviation) szórásSDF (System Data Format)

szabványos szöveges adatállomány

search keressearching kereséssector szektor, körcikksecurity biztonságseek keresseek time keresési idôsegment szegmens, metszet, szelet,

részselect kiválasztselection kiválasztássemantical szemantikai, jelentéstanisemantics szemantika, jelentéstansemicolon pontosvesszôsemiconductor félvezetôsend küldsequence szekvencia, sorrend,

sorozatsequential szekvenciális, sorrendiserial sorozat-, sorozatos, sorrendi,

sorosserial acces soros hozzáférésserial interface soros interfaceserial number sorozatszámserial port soros portseries sor, sorozat, hatványserver szerver, kiszolgálósession munkaszakaszset halmaz, beállít, kiszed (betut)set up beállítsetup beállításshadow árnyék, árnyékol, árnyalsheet lap, ívshell vázshift váltó, változtat, eltolshift registersign jel, jelzés, elôjel, jelezsignal jel, jelzés, jelezsignificance szignifikancia, fontosságsigning-on message bejelentkezô

üzenetsimplex szimplexsimulation szimulációsimulator szimulátorsingle spacing egyes sortávolság

(gépírásnál)size méretskip átugrik, átlép

49

slash per jel (/)slot rés, nyílássmoothing simítássoftware szoftversoftware package szoftvercsomag,

alkalmazói programsoftware tool szoftverfejlesztési

eszközsort rendezsorting rendezéssource forrássource code forráskódspace üres karakter, térköz, helyspace bar szóköz billentyuspacing ritkítás, térköz, sortávolságspeech synthesis

beszédszintetizálásspeed sebességsplit szétválaszt, szétosztsplit screen osztott képernyôspread kiterjesztspreadsheet táblázatos kalkulációs

programsprite mozgatható grafikai figuraSQL (Structured Query Language)

struktúrált adatbázis-lekérdezô neylv

square négyzetsquare root négyzetgyökSS (single sided) egyoldalas

mágneslemezstack veremtárstack-pointer veremtár mutatóstacked bar egymásra rakott

oszlopdiagramstand-alone magában állóstandard szabványstandard deviation szórásstandby készenlétstar network csillaghálózatstart kezd, rajtolstatement állítás, kijelentés, parancsstationery levélpapírstatistical methods statisztikai

eljárásokstatistics statisztikastatus állapot, státuszstatus line állapotjelzô sorstep lépésstepwise lépésenkéntistochastic szotchasztikusstochastic process sztochasztikus

folyamatstore tárol, tároló, társtored program tárolt programstoring device tárolóeszközstreamer sztrímer, szalagos

adattömegtárolóstrike üt, leüt (billentyut)

strikethrough áthúzottstring sztring, karakterfuzér,

jelsorozatstroke ütés, leütés, billentyuzésstroked font vektorral megadott

karakterkészletstructure struktúra, szerkezetstructured programming struktúrált

programozásStudent's t-distribution normális

eloszlásstyle stílusstylesheet stíluslapsubroutin szubrutinsubscript alsó indexsubset részhalmazsubstring részsztringsubtitle alcímsubtotal részösszegsubtract kivonsubtraction kivonássuffix toldaléksum összeg, összegezsupercomputer szuperszámítógépsuperscript felsô indexsupport támogatsure biztossuspend félbeszakít, felfüggesztswitch kapcsoló, kapcsolsymbol jel, szimbólumsynchron szinkronsynchronization szinkronizálássyntactical mondattanisyntax mondattan, szintaktikasynthetiser szintetizátorsynthetize szintetizálsystem rendszersystem disk rendszerlemez

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1.7 GlossaryAccess time: The time required to obtain data from main memory or a storage device, such as a

floppy diskette or a hard disk.

Acoustic coupler: A device for transmitting data over phone lines by converting electrical signals into audio signals, and vice versa. See data communications and modem.

Applications: A specific program or task, such as sorting employee records, to which a computer solution can be applied.

Application program: A computer program designed to meet specific user needs such as a program that controls inventory or monitors a manufacturing process.

Arcnet: Simple computer network of star topology. The terminals are connected to each other with coaxial cable via hubs. Its transfer rate is 2.5 Mbaud, the maximum number of the users is 255.

Architecture: In the case of computers, architecture often refers to the design or organization of the central processing unit (CPU).

Artificial Intelligence (AI): Methods of solving difficult problems by the computer. Its main fields are such as game theory, decision making, learning systems, expert systems, optical recognition, natural language interfaces, machine translation, speech understanding and speech generating, etc.

ASCII (American Standard Code for Information Interchange): Code that has assigned a binary number to each alphanumeric character and several non-printing characters used to control printers and communication devices. The binary number (code) assigned to each alphanumeric character is called ASCII code (e.g., A=65, B=66, C=67, etc.).

ASCII keyboard: A keyboard that sends an ASCII character to a computer when the user presses the corresponding key.

Assembler: Program that compiles an assembler source program to a machine code object program.

Assembly: Low level programming language.

Asynchronous: A communications method in which data is sent as soon as it is ready, in contrast to methods where data is sent at fixed intervals.

AT (Advanced Technology): Personal computer type which is operated by the Intel 80286 processor

AUTOEXEC.BAT: A special batch file with DOS commands that will be executed during the boot-up process.

Background: Refers to one or more non-interactive services running on a personal computer while the user is using another interactive (foreground) service.

Background processing: The automatic execution of a low-priority computer program when higher priority programs are not using the system's resources. See foreground processing.

Backup: Copying of one or more files onto a storage medium for safekeeping, in case if the original get damaged or lost.

BASIC: (Beginners' All-purpose Symbolic Instruction Code) a widely used interactive programming language developed by Dartmouth College by János Kemény. It is specially designed for personal computers and beginners.

Batch processing: The technique of executing a set of computer programs without human interaction or direction during their execution. Under certain conditions, direct interaction is possible.

Baud: Unit of data transmitting and receiving speed, roughly equal to a single bit per second. Common Baud rates are 110, 300, 1,200, 2,400, 4,800, and 9,600.

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Bidirectional: (1) Ability to transfer data in either direction, especially on a bus. (2) Ability of a print head to print from right to left and from left to right, which increases print speed.

Binary: (1) Number system with only two digits - 0 and 1 - in which each symbol represents a decimal power of two. (2) Any system that has only two possible states or levels, such as a switch that is either on or off. This is represented in a computer circuit by the presence of current (equivalent to "l") or its absence (equivalent to "0"). All computer programs are executed in binary form.

Bit: Binary digit, which can have only two possible values - 0 or 1. It is the smallest unit of data recognized by the computer All data (letters, numerals, symbols) handled by a computer are digitized, i.e., expressed entirely as a combination of bits - Os and ls.

Bit-map graphics: A technology that allows control of individual pixels on a display screen to produce graphic elements of very good resolution, permitting accurate reproduction of arcs, circles, sine waves, or other curved images that block-addressing technology cannot accurately display.

Board: Also circuit board. A plastic resin board containing electronic components such as chips and the electronic circuits necessary to connect them. See option module.

Bubble jet printer: New version of ink jet printers. It shoots hot ink bubbles onto the paper. Its resolution is between 300-400 dpi.

Buffer: A temporary storage area for data, frequently used to hold data passed between computers or other devices, such as printers, which operate at different speeds or different times.

Bus: A group of parallel electrical connections that carry signals between computer components or devices.

Byte: The number of bits used to represent a character For personal computers, a byte is usually eight bits so it can represent a number between 0 and 255.

C: A high power, low level programming language that supports both the structured programming and the effective using of the processor. Therefore, it is the most popular language of the PCs and UNIX workstations.

Cache: Memory that accelerates disk operations by buffering data. It can be created in the RAM by using a device driver (e.g., SMARTDRV.EXE). The new 386 and 486 machines automatically create it in a separate RAM chip.

Cathode-ray tube (CRT): A vacuum tube that generates and guides electrons onto a fluorescent screen to produce such images as characters or graphic displays on video display screens.

Central processing unit (CPU): Electronic component in a computer which control the transfer of data and perform arithmetic and logic calculations.

CD-ROM: Storage device that uses optical compact discs of 600 Mbyte capacity. Commonly used media to distribute large databases such as dictionaries, encyclopedias, bibliographies. Originally, it was read only memory but the new versions are writable one or more times by the user.

CGA (Color Graphics Adapter): Graphic card of the first ATs. Its resolution is 640x200 (in two color mode) or 320x200 (in four color mode)

Character: A printable letter (A-Z), numeral (0-9), or symbol (, % $ .) used to represent data, or text symbols that are not displayed on screen or printouts, such as a space, tab, or carriage return.

Character code: A code that assigns numerical values to characters, such as ASCII code.

Character printer: A printer that prints one character at a time like a typewriter See lineprinter

Chip: A piece of semiconductor material containing microscopic integrated circuits.

Circuit: (1) A system of semiconductors and related electrical elements through which current flows. (2) In data communications, the electrical path providing one-way or two-way communication between two points.

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COBOL: (COmmon Business-Oriented Language) A high-level programming language developed for business applications involving complex data records (such as personnel files or customer accounts) and large amounts of printed output.

Command: A user instruction to the computer, generally given through a keyboard, which can be a word, mnemonic, or character that causes a computer to perform a predefined operation.

Compatibility: (1) The ability of an instruction, program, or component to be used on more than one computer (2) The ability of computers to work with other computers that are not necessarily similar in design or capabilities.

Compiler: A program that translates a source code (text-file) to an object code. Then a linker program generates the machine code program from the object code using a library of routines.

Computer network: An interconnection of computer systems, terminals, and communication facilities.

CONFIG.SYS: A text file with special DOS commands which are executed when the computer is booting up. It also specifies device drivers for your computer. See also Device driver.

Configuration: The assortment of equipment (disks, diskettes, printers, etc.,) in a particular system.

Co-processor: (1) A chip that can make mathematical operations faster. There are just as many types of it as the processors (8087 for XT, 80287 for AT286, 80387 for AT386, etc.). It should be plugged in the appropriate socket on the mother-board. (2) Any microprocessor, which can take over some of the work of the CPU. (E.g. floating point and graphical co-processors.)

Core: The older type of non-volatile computer memory made of ferrite rings that represents binary data by switching the direction of polarity of magnetic cores. Most modern computers use integrated circuits, which are faster than core memory, but volatile.

CPI: See Pitch.

CP/M (Control Program for Microprocessors): An operating system that was used by many 8 bit personal computers.

CPU: See central processing unit.

CRT: See cathode-ray tube.

Cursor: A movable, blinking marker - usually a box or a line - on the terminal video screen that defines the next point of character entry or change.

Daisywheel: A print head that forms full characters rather than characters formed of dots. It is shaped like a wheel with many spokes, with a letter, numeral, or symbol at the end of each spoke. The printing technology is the same as a typewriter. See dot-matrix printer.

Data: Facts, numbers, letters and symbols stored in the computer. For personal computer users, data can be thought of as the basic elements of information used, created or otherwise processed by an application program. Examples of data are the employee names, weekly deductions from salary, projected sales and fuel consumption.

Database: A large collection of organized data that is required to perform a task. Typical examples are personnel files or stock quotations.

Data communication: The movement of coded data from a sender to a receiver by means of electrically transmitted signals.

Data diskette: A diskette that is used entirely or primarily to contain data files.

Data processing: The application in which a computer works primarily with numerical data. Many computers can perform data processing and word processing.

DEBUG: Simple monitor program of the MS-DOS.

Debugger: A program which can search for the mistakes ("bugs") in a program.

Dedicated computer: A computer built for one special function such as controlling laboratory equipments.

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Delimited file: Compact file format for transferring data between database management systems, spreadsheets, etc. The character series are quoted, the numbers and the pieces of data (fields) are separated with a delimiter (e.g., with commas).

Desktop Publishing (DTP) System: Computer system with high resolution monitor, printer and scanner. DTP programs (Xerox Ventura, Aldous PageMaker, etc.) show the same picture that will be printed, and they allows editing texts and images in various formats.

Device: In computers, a piece of hardware that performs a specific function. Input devices (e.g., keyboard) are used to get data into the CPU. Output devices (e.g., printers or display monitors) are used to take data out of a computer in some usable form. Input/output devices (e.g., terminal or disk drive) are able to perform both input and output of data.

Device driver: See driver.

Diagnostic: A program that checks the operation of a device, board or other component for malfunctions and errors, and reports its findings.

Direct memory access (DMA): A method for transferring data to or from a computer's memory without CPU intervention.

Disk: A rigid, flat, circular plate with a magnetic coating for storing data. Physical size and storage capacity of disks can vary.

Disk/diskette drive: A unit used to read data from or write data onto one or more diskette.

Diskette: A flexible, flat, circular plate permanently housed in a black paper envelope with magnetic coating that stores data and software. Standard sizes are 5 1/4-inches and 3 1/2 inches in diameter.

Display screen: A device that provides a visual representation of data; a TV like screen. See cathode-ray tube.

Distributed data processing: A computing approach, where an organization uses computers in more than one location, rather than one large computer in a single location.

DMA: See direct memory access.

DOS (Disk Operating System): Trademark of the operating system of the IBM PCs. It has two versions: PC-DOS and MS-DOS (Microsoft-DOS).

Dot-matrix printer: A printer that forms characters from a two-dimensional array of dots. More dots in a given space produce characters that are more legible. See also daisywheel.

Double density: Special recording method for diskettes that allows them to store twice as much data as in normal, or single-density recordings.

Downtime: Period of time when a device is switched off.

DPI (Dot Per Inch): Unit of measurement for the resolution of the printers and scanners. See Resolution.

Draft-quality printer: A printer, usually high-speed, that produces characters of lesser quality than a typewriter. See letter-quality printer.

Drive: A peripheral device that holds a disk or diskette so that the computer can read data from and write data onto them.

Driver: A program that allows the operating system to communicate with a peripheral device. The program usually has SYS, EXE or COM extension. See also CONFIG.SYS.

Electronic mail (e-mail): A feature that allows short memos or messages to be sent to another computer via cable.

EMS: See expanded memory.

Emulator: A program that allows a computer to imitate a different system, thus enabling different systems to use the same data and programs to achieve the same results; but with possibly different performance rates.

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EPROM (Erasable Programmable Read Only Memory): A memory chip that can be used in the same way as a ROM chip. The only difference is that its content can be clear with UV-light and then new data can be fed into it.

Ergonomics: The science of human engineering which combines the study of human-body mechanics and physical limitations with industrial psychology. Constant work with computers can lead to health problems in some users such as: eyestrain; neck and back pain; hand, wrist and elbow pain; stress; tension headaches, dizziness, nausea, tension and irritability.

Error message: Text displayed by the computer when an incorrect command is typed, which explains the problem and indicates what to do next.

Ethernet: Local area network of bus topology. Its transfer rate is 10 Mbaud, the maximal number of terminals is 1024. It can be used by both Novell Netware and UNIX.

Expanded memory (EMS): DOS cannot use the memory above 640 Kbyte. The EMS manager located in the upper memory block divide this memory to pages and when a program requires the content of the EMS the manager copies it to the upper memory block where DOS can access it. The EMM386.EXE program (part of DOS) can be used only on 386 and 486 machines, the 286 ATs need a different program. Other method of using this memory is called extended memory (XMS).

Expansion card: Electric board (controller card) that can be plugged into an expansions slot. The disk controller and the graphic card are essential for operating the computer. The input/output card is used to connect the peripherals (e.g., printer, mouse) to the computer. Some other peripherals (e.g., scanners) have their own controller card.

Expansion slot: Socket on the mother board for plugging expansion cards into it. Usually there are 8 expansion slots on the mother board.

Export: Generate files that can be read by an other application program. See also import.

Extended memory (XMS): One of the methods of using the memory above 640 Kbyte in ATs. The XMS memory manager (HIMEM.SYS) ensure accessing all the memory. It also allows loading DOS to the upper memory block. Nowadays most of the programs require XMS (e.g., MS-Windows).

Extension: A suffix added to a filename. An extension may be any three legal filename characters.

Fanfold paper: A continuous sheet of paper whose pages are folded in accordion-style and separated by perforations. Long documents can be printed on it without inserting paper manually.

Field: The smallest independent item of a record in a database.

File: A collection of logically related records or data treated as a single item. A file is a record where data is stored on a disk or diskette, so it can be used later.

Filename: The sequence of alphanumeric characters assigned by a user to identify a file which can be read by both the computer and the user. On PCs, a file name has a maximum length of eight alphanumeric characters and an extension of three characters can be added to it.

Flexible disk: See diskette.

Floppy disk: See diskette.

Font: A complete set of letters, numerals, and symbols of the same typestyle of a given typeface. Examples of typefaces are TimesRoman and Helvetica. Examples of fonts are TimesRoman Italic, TimesRoman Bold, and TimesRoman Bold Italic.

Foreground processing: Top-priority processing; it has priority over background (lower-priority) processing.

Format: The way text appears on a page. There are three types of formats: font and font size (character formats); paragraph alignment (paragraph formats); and overall page design (division formats).

Formatting: (1) Preparing the diskette for writing data to it. (2) Designing the appearance of text in a document.

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Formfeed: Automatically advances a roll of fanfold paper to the top of the next page.

FORTRAN: (Formula Translation): A widely used high-level programming language suitable to solve problems that can be expressed in algebraic formulas. It is generally used in scientific applications.

Function key: A key that causes a computer to perform a function (such as clearing the screen) or execute a program.

Graphics: Usage of lines and figures to display data, in contrast to the use of printed characters. See bit-map graphics.

Hardcopy: Output something in a permanent form (usually on paper or paper tape) rather than in temporary form as on a CRT or visual display.

Hard disk: A disk that is not flexible, such as a Winchester disk. It is more expensive than a diskette but is capable of storing much more data. See disk and Winchester disk.

Hardware: The physical equipment that makes up a computer system.

Hardwired: Refers to a permanent (opposite of a switched connection) physical connection between two points in an electrical circuit or between two devices linked by a communications line. When using a personal computer, local connections are typically hard-wired, whereas all connections through a modem are switched because they use telephone lines.

Head: A component that reads, writes or erases data on a storage medium such as a diskette or disk.

Help service: Messages displayed on the video screen that provide information on how to use applications and other system services.

IC: See integrated circuit.

Impact printer: A printer that forms characters on paper by striking an inked ribbon with a character-forming element.

Import: To read data (texts, numbers, images) into an application program from files generated by an other program. There are common file formats and converters to make it easier. See Export.

Index file: A table extracted from a database. It contains the localization of the given key expressions in the database to accelerate searching.

Ink jet printer: A type of desktop printer that prints by sparing ink on paper. Ink jet printers can print in black and white and color in varying resolution.

Instruction: A command that tells the computer what operation to perform next.

Integrated circuit (IC): A complex electronic circuit on a single chip.

Interactive: Capable of carrying on a dialogue through the keyboard with the user, rather than simply responding to commands.

Interface: An electronic circuit that connects an external device, such as a printer, to a computer.

Job: A task (program) for a computer to execute, such as reading a disk or printing a file.

K: The symbol for the quantity 210 or 1024. The K is uppercase to distinguish it from lower-case k, which is a Standard International Unit for "kilo," or 1,000.

Keyboard: The set of keys on a terminal that allows alphanumeric characters or symbols to be transmitted when keys are depressed. It inputs text and instructions to the computer

Kbyte (KB): 1,024 bytes.

LAN (Local Area Network): Computer network of small distances (max. 5 km). It is typically used inside an institution (hospital, university, etc.). See also Arcnet, Ethernet, Novell, UNIX.

Laser printer: High resolution printer based on the principle of electrostatic copiers (Xerox machines). The Hewlett-Packard printers are regarded as world standards (HP LaserJet+, II, III, IV). The resolution is between 300 and 600 dot per inch.

Laptop computer: A portable (5-7 kg) computer with liquid crystal monitor.

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Large-scale integration (LSI): Combination of about 1,000 to 10,000 circuits on a single chip. Typical examples of LSI circuits are memory chips, microprocessors, calculator chips and watch chips.

Letter-quality printer: The printer used to produce final copies of documents. It provides a printing quality of a typewriter.

Lineprinter: High-speed printer that prints an entire line of characters at a time.

List processing: The word processing application that permits many copies of a form document to be produced, with certain information changing from one copy to the next (e.g., the production of personalized form letters).

Local: Hardwired connection of a computer to another computer, terminal, or peripheral device such as in a local area network. See remote.

Local Area Network: See LAN.

LSI: See large-scale integration.

Macro: A series of key-strokes. Allow the user to save keystrokes needed to perform a specific operation, and then initiate them by pressing a key.

Magnetic tape: Magnetic tape used as mass storage media. Since the data stored on magnetic tape can only be accessed serially, it is not practical for use with personal computers. However, it is often used as a back up device.

Mainframe: A computer that is physically large and provides the capability to perform applications requiring large amounts of data (e.g., for large-scale payroll system). These computers are much more expensive than microcomputers or minicomputers.

Main memory: See memory

Mass storage: A device like a disk or magnetic tape that can store large amounts of data readily accessible to the central processing unit.

Mbyte (MB): 1,048,576 (1020) bytes, 1024 (1010) Kbytes.

Medium: The physical substance upon which data is recorded, for example, magnetic disks, magnetic tape or punched cards.

Memory: (1) The main high-speed storage area in a computer where instructions of a program can be found temporarily. (2) A device in which data can be stored and from which it can later be retrieved.

Menu: A list of options from which the user selects an action to be performed by typing a letter or by positioning the cursor by using the arrow keys or the mouse.

Menu-driven: A computer system that primarily uses menus as its user interface rather than a command language.

Microcomputer: A computer which is physically very small - it can fit on or under a desk - and which is based on large-scale integration (LSI) circuitry. It is usually the least expensive of the computer types.

Microprocessor: A single-chip central processing unit incorporating LSI technology.

Minicomputer: A type of computer whose physical size is usually smaller than a mainframe. In general, its performance exceeds that of microcomputers. Since minicomputers are more modular than mainframes, they can be configured to provide better price/performance systems. The most popular mini is the VAX (manufactured by the Digital Equipment Corporation).

Mnemonic: A short, easy-to-remember name or abbreviation. Many commands in programming languages are mnemonics.

Modem (Modulator/Demodulator): A device that converts computer signals (data) into high-frequency communications signals, and vice versa. These high-frequency signals can then be sent over telephone lines.

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Monitor (hardware): A television-like device that can be used as an output display See also cathode-ray tube and display screen.

Monitor (software): Part of the operating system. Allow the user to enter programs and data into memory. Run programs and check the registers of the processor. On IBM PCs its name is DEBUG.

MOS: Metal-oxide semiconductor, the most common form of LSI technology.

Mother board: The base electronic circuit board of the computer which contains the microprocessor, the ROM, the RAM and expansion slots for the disk drivers, I/O ports, graphics card, etc.

Multi-copy form: A preprinted, multiple form that contains carbon paper between the pages (e.g., tax forms and credit card receipts).

Multi-key sort: Using more than one parameter to qualify a record for inclusion in a specified group or to order a set of records.

Multi-processing: Execution of two or more computer programs by a computer which has only one processor.

Multi-programming: A scheduling technique that allows more than one job to be in an executable state at a time. Thus, even with one CPU, more than one program can appear to be running at a time because the CPU is giving small slices of its time to each executable program. See multi-tasking.

Multi-tasking: The execution of several tasks "at the same time without having to complete one before starting another Although computers can perform only one task at a time, the speed at which a computer operates is so fast that it appears as though several tasks are being performed simultaneously. See multi-programming.

Network: A group of computers that are connected to each other by communications lines to share information and resources. See computer network.

Nonvolatile memory: Memory that does not lose its contents when a processor's power supply is shut off or disrupted.

Novell NetWare: The most popular network operating system of IBM PCs. It runs on a PC equipped with a high capacity hard disk. The network can be either Arcnet or Ethernet. It mainly ensures file-server functions: the terminals can share the disk of the server, but the programs should be loaded into the terminal's memory before starting them. Therefore, there is high degree of data transfer in the system which limits the performance.

Optical Character Recognition (OCR): OCR programs can recognize the characters on a scanned image and store the text in the form of ASCII codes.

On-line: Directly under the control of the computer; data is introduced into the CPU immediately

Operating system: A collection of computer programs that controls the overall operation of a computer and performs tasks as assigning places in memory to programs and data, processing interrupts, scheduling jobs and controlling the overall input/output flow of the system.

Option module: A plug-in electronic circuit. Can be inserted into a free slot of the computer. See board.

Parallel transmission: Sending more than one bit at a time. See serial transmission.

Parity: A one-extra-bit code used to detect recording or transmission errors by making the total number of "l" bits in a unit of data - including the parity bit itself - odd or even.

Peripheral: A device that is external to the CPU and main memory, e.g., printer, modem, or terminal but connected to it by appropriate electrical connections.

Pica: A unit of measure used in typography. There are twelve points in a pica and six picas in an inch. See also Point, Pitch.

Pitch: A horizontal measure of the number of characters per inch (cpi). Most typewriters and printers use 10-pitch (10 characters per inch) or 12-pitch (12 character per inch).

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Pixels (Picture elements): Locations on a display screen that are used to form images on the screen. For graphics displays, screens with more pixels generally provide higher resolution. See bit-map graphics.

Point: A unit of measure used in typography. There are 12 points in a pica and 72 points in an inch.

Port: Physical area of the connection of a communications line. This line can be between the CPU and anything external to it, such as a printer, another computer, a modem, or another communication line.

PostScript: A page-description language, developed by Adobe Systems Inc., that is used by high resolution printers.

Power supply: A transistor switch that converts AC into DC; supplies components such as integrated circuits, monitors and keyboards; and steps down the power supplied to some components.

Printer: The device that produces a paper copy of a document (hard copy output). There are two types: draft-quality and letter-quality printers. Unlike a terminal, there is virtually no communication from printer to CPU.

Printhead: The element in a printer that forms a printed character.

Print queue: See Spooler.

Printwheel: See daisywheel.

Printout: An informal expression referring to almost anything printed by a computer peripheral device; any computer-generated hard copy.

Program: The complete sequence of instructions and routines needed to solve a problem or to execute directions on a computer. The machine code program files have the extension COM (COMmand file) or EXE (EXEcutable program).

Program disk: A disk containing the instructions of a program.

Programming language: The words, mnemonics and/or symbols, along with the specific rules allowed in constructing computer programs.

Protocol: Complex entirety of rules for the communication between two computer systems.

RAM (Random Access Memory): Memory that can both be read and written into (i.e., altered) during normal operation. RAM is the type of memory used in most computers to store the instructions of programs currently running.

Real-time: A function (data access, display, etc.) performed during the course of a process, without interpreting it. It refers to computer systems or programs that performs a computation meanwhile a physical process transpires. The results can be recorded or used to guide the physical process, e.g., computers that guide airplane landings.

Record: A collection of related data items.

Remote: Not hard-wired; communicating via switched lines such as telephone lines. Usually refer to peripheral devices (e.g., printers, video terminals) that are located in a different location than the CPU.

Resolution: (1) Rate of dots per inch (dpi) scanned or printed. The greater the number of dpi, more detail is visible in the image or printout. Recent, equipment can work at 300-600 dpi. (2) The resolution of screens and graphic cards are given by the number of horizontal and vertical pixels. The highest SVGA resolution is 1280x1024.

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Reverse video: A feature on a display unit that produces the opposite combination of characters and background from that which is usually employed, i.e. white characters on a black screen, if having black characters on a white screen is normal.

ROM (Read Only Memory): Memory containing fixed data or instructions that is permanently loaded during the manufacturing process. A computer can use the data in the ROM but cannot change it.

Scanner: An input device that reads printed or typed information directly into your PC. Handy scanners can scan only a narrow stripe (10 cm), the larger models can read A/4 or A/3 sheets.

Screen: (1) The display surface of a video monitor (2) The pattern or information displayed on the screen.

SCSI (Small Computer System Interface): An interface that allows hard disks and other high-performance peripherals (e.g., scanners, CD-ROM drives) to be attached to Macintosh, PC and UNIX computer systems.

Self test: A procedure where a program or peripheral checks its own operation.

Sequential access: Refers to devices, like magnetic tape, from which data or instructions can be retrieved only by passing through all locations between the one currently being accessed and the desired one.

Serial access: See sequential access.

Serial transmission: Sending one bit at a time. See parallel transmission.

Single-thread: Refers to a simple operating system that executes any given task from beginning to end without interruption, opposite of the multi-tasking system.

Softcopy: Alphanumeric or graphical data (or both) presented in temporary form, such as on a video screen.

Software: The tasks or programs that makes the computer perform a particular function.

Sort: Rearranging the records in a file so that the order is convenient to the user.

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Understanding the technology...

Spooler: A program that sends files to the printer. The spooler hold files in the print queue, then sends another one when the printer is ready. The spooler allows you to continue working on another files while a file is being printed. The networks use similar method for printing on a central printer.

Storage unit: Where documents can be saved for later use. Usually a disk or diskette.

String: Series of alphanumeric characters.

System: A combination of software and hardware that performs specific processing operations.

System board: See mother board.

Task: A program under execution.

Terminal: An input/output device used to enter data into a computer and record the output. Terminals are divided into two categories: hard copy (e.g., printers) and soft copy (e.g., video terminals).

Terminal emulation: A communication method in which a terminal acts as a terminal of a different design so that it can be used on various systems. For example, PCs can be used as UNIX terminals by using a terminal emulator software.

Thermal transfer printer: A type of printer that prints by bonding pigment or paper with heat. These printers generally can print in higher resolution than ink jet printers.

TIFF (Tag Image File Format): An industrial standard of image file format supported by many applications. These files have TIF extension.

Timesharing: Providing service to many users by working on each application by switching between them in predefined intervals.

Track: The portion of a moving storage medium, such as a disk or tape, that is accessible to a given read/write head position.

Tractorfeed: The mechanical apparatus used to move paper through a printer The roller that moves the paper has sprockets on each end. They fit into the fanfold paper's matching holes.

Turnkey system: A computer that is ready to be used without adding any hardware or software; it is ready-made for a given task.

Typeface: See font.

UMB: See upper memory block.

Upgrade: To expand your personal computer or software as new versions are developed, or to enhance existing features.

Upgrading: If you have a registered software the manufacturer sales you the new version for a reduced price.

Upper Memory Block (UMB): The blocks of the memory area between 640 K and 1 M in ATs. See extended memory.

Video monitor: See monitor (hardware).

Video terminal: A terminal that displays data on a CRT

Volatile memory: Memory that loses its contents when power is removed unless battery back up is available. See core and non-volatile memory.

VT: Video terminal. The common trademarked name of DIGITAL's VT family of video terminals.

Winchester disk: A hard disk permanently sealed in a drive unit to prevent contamination of the heads; this virtually eliminates the need for adjustment by service personnel. The disk is capable of storing larger amounts of data than a diskette.

Window: An area on the screen where you are running an application (e.g., in Microsoft Windows) or a file is being shown.

Windows: Graphic operating system of the Microsoft Corp.

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Word: The highest number of bits a computer can handle during operation. Usually subdivided into bytes.

Word processing system: A system that processes text, performing functions as paragraphing, paging, left and right justification, rearrangement of lines and printing the text.

Word-wrapping: The automatic shifting of words of a line to left, when the length of the line exceeds the actual paragraph (screen) width.

Workstation: High performance microcomputer (in UNIX systems). Workstations with a large hard disk can be used as servers, diskless workstations can be used as intelligent terminals.

WYSIWYG (What You See Is What You Get): Same image will appear on the screen and the printer.

XMS: See extended memory.

X-terminal: High resolution graphic terminal used in UNIX systems.

Zoom: Enlarging or reducing the size of a window.

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1.8 The Hungarian Keyboard (Used at the DOTE)

+-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ¦Í¦ ¦'¦ ¦"¦ ¦+¦ ¦!¦ ¦%¦ ¦&¦ ¦/¦ ¦(¦ ¦)¦ ¦=¦ ¦Ö¦ ¦Ü¦ ¦Ó¦ ¦B¦ ¦í¦ ¦1¦ ¦2¦ ¦3¦ ¦4¦ ¦5¦ ¦6¦ ¦7¦ ¦8¦ ¦9¦ ¦0¦ ¦ö¦ ¦ü¦ ¦ó¦ ¦S¦ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +---+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +---+ ¦Tab¦ ¦Q¦ ¦W¦ ¦E¦ ¦R¦ ¦T¦ ¦Y¦ ¦U¦ ¦I¦ ¦O¦ ¦P¦ ¦U¦ ¦Ö¦ ¦ ¦ ¦ ¦ ¦q¦ ¦w¦ ¦e¦ ¦r¦ ¦t¦ ¦y¦ ¦u¦ ¦i¦ ¦o¦ ¦p¦ ¦ú¦ ¦ö¦ ¦ ¦ +---+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ¦ ¦ +-----+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ ¦ ¦Caps ¦ ¦A¦ ¦S¦ ¦D¦ ¦F¦ ¦G¦ ¦H¦ ¦J¦ ¦K¦ ¦L¦ ¦É¦ ¦Â¦ ¦Enter¦ ¦Lock ¦ ¦a¦ ¦s¦ ¦d¦ ¦f¦ ¦g¦ ¦h¦ ¦j¦ ¦k¦ ¦l¦ ¦é¦ ¦á¦ ¦ ¦ +-----+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-----+ +-------+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-------+ ¦ Shift ¦ ¦Z¦ ¦X¦ ¦C¦ ¦V¦ ¦B¦ ¦N¦ ¦M¦ ¦;¦ ¦:¦ ¦Ü¦ ¦ Shift ¦ ¦ ¦ ¦z¦ ¦x¦ ¦c¦ ¦v¦ ¦b¦ ¦n¦ ¦m¦ ¦,¦ ¦.¦ ¦ü¦ ¦ ¦ +-------+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-------+ +-----+ +-----+ +-------------------+ +-----+ +-----+ ¦Ctrl ¦ ¦ Alt ¦ ¦ Szóköz ¦ ¦ Alt ¦ ¦Ctrl ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +-----+ +-----+ +-------------------+ +-----+ +-----+

1.9 The IBM Character Set

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