Few things happen at the right time, and the rest do not happen at all. The conscientious historian will correct these defects. Mark Twain

The evolutionary path of operating systems

Time Sharing Each user has the feeling that he owns his portion of the machine. Each user has the feeling that he owns his portion of the machine.

DEC introduced TOPS-10 in 1972  files - blocks of data could be created, modified, stored, recalled from a terminal  file names – 1 to 6 characters followed by a period, then a 3-character extension  small portion of TOPS-10 always present in core memory

Tops-10  other programs stored on the disk and called up as needed  user could move files to and from i/o equipment  text editor  dynamic debugging tool

Time Sharing Since computers were expensive, some companies tried to sell time on their machines. It did not work Most people wanted to use the machine at the same time

Gordon 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 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 Calculators o 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 65 Few mainframes could do this without custom-written software.

The Personal Computer Changes the World as We Know It

The MICRAL Realisations Etudes Electroniques The first general-purpose computer based on a microprocessor, the Intel 8008 Thi T. Truong

Altair Lost its data when the power was shut off Data transformed into audio tones and stored on magnetic tape

Software: Basic The eight design principles of BASIC 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 (while keeping the language simple for beginners).Allow advanced features to be added for experts (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 Software the 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 1978

The solution to the storage problem Gary Kildall The floppy disk drive Big Advantage: Random Access

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