Few things happen at the right time, Few things happen at the right time, and the rest do not happen at all. and the rest do not happen at all. The conscientious historian will The conscientious historian will correct these defects.correct these defects.
Mark TwainMark Twain
Time SharingTime Sharing
Each user has the feeling that he Each user has the feeling that he owns his portion of the machine.owns his portion of the machine.
DEC introduced TOPS-10 DEC introduced TOPS-10 in 1972in 1972
files - blocks of data could be created, files - blocks of data could be created, modified, stored, recalled from a terminalmodified, stored, recalled from a terminal
file names – 1 to 6 characters followed by a file names – 1 to 6 characters followed by a period, then a 3-character extensionperiod, then a 3-character extension
small portion of TOPS-10 small portion of TOPS-10 always present in core memoryalways present in core memory
Tops-10Tops-10 other programs stored on the disk other programs stored on the disk
and called up as neededand called up as needed
user could move files to and from i/o user could move files to and from i/o equipmentequipment
text editortext editor
dynamic debugging tooldynamic debugging tool
Time Sharing• Since computers were expensive, Since computers were expensive,
some companies tried to sell time some companies tried to sell time on their machines.on their machines.
• It did not workIt did not work
• Most people wantedMost people wanted to use the machine to use the machine at the same time at the same time
Gordon BellGordon Bell
The semiconductor density has really been the driving force of development. As you reach different density levels, different machines pop out of that in time.
The MicroprocessorThe Microprocessor• Late 1960’s metal oxide
semiconductor (MOS) put more logic elements on a chip
• Intel marketed the first in 1972
• Made hand held calculators possible
Intel 8008
Hand-Held CalculatorsHand-Held Calculatorso It could:
o Execute short programs
o Compute logarithms
o Compute trigonometric functions
o Use floating-point arithmetic to 10 digits of precision
Hewlett-Packard 65Hewlett-Packard 65
Few mainframes could do this Few mainframes could do this without custom-written software.without custom-written software.
The MICRALThe MICRALRealisations Etudes ElectroniquesRealisations Etudes Electroniques
The first general-purpose computer based on a The first general-purpose computer based on a microprocessor, the Intel 8008microprocessor, the Intel 8008
Thi T. Truong
AltairAltair 8800 880019741974
•Lost its data when the power was shut off
•Data transformed into audio tones and stored on magnetic tape
Software: BasicSoftware: BasicThe eight design principles of The eight design principles of BASICBASIC were: were:
• Be easy for beginners to use. Be easy for beginners to use.
• Be a general-purpose programming language. Be a general-purpose programming language.
• Allow advanced features to be added for experts Allow advanced features to be added for experts (while keeping the language simple for beginners). (while keeping the language simple for beginners).
• Be interactive. Be interactive.
• Provide clear and friendly error messages. Provide clear and friendly error messages.
• Respond fast for small programs. Respond fast for small programs.
• Not require an understanding of computer hardware. Not require an understanding of computer hardware.
• Shield the user from the operating system. Shield the user from the operating system.
System SoftwareSystem Softwarethe final piece of the puzzlethe final piece of the puzzle
• Paul Allen showed the magazine to Bill Gates
• They wrote a 4K, 8K, and an “extended” version of BASIC
Microsoft team 1978Microsoft team 1978
The solution to the storage problem
1942-1994
Gary KildallGary Kildall
The floppy disk drive
Big Advantage: Random Access