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

The evolutionary path of The evolutionary path of operating systemsoperating systems

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

Computer on a chip

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 Personal Computer Changes the World as We Know It

1972-19771972-1977

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

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