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Mainframes are too expensive to be single user machines.
John McCarthy @ MIT
- advocates the virtual machine idea
- every user has the illusion of being the "sole" user of the machine
- Teletype I/O - Model ASR-33
- compute between keystrokes
1962 an experimental system on a 7090
- expands to Compatible Time Sharing System (CTSS) on upgraded 7094
- supports a few users
Project MAC (Man and Computer)
- Selects a GE 635 rather than an IBM 360
- 360's not designed to support timesharing
- IBM responds with Model 67
- and later with System 370
MULTICS
- a time sharing system on the GE 635
- in use by 1969
Unix @ Bell Labs
- preliminary work on PDP-8 and eventually PDP-11
Other, larger time sharing machines
-DEC's PDP-10
-Scientific Data System's SDS-940
Scientific Data Systems
1961 - founded by Max Palevsky, a philosopher
- within a year, Model 910
- good I/O, silicon transistors
1965 - Introduces Model 930
-explicitly marketed for time-sharing (2, 166)
1967 - Introduces Sigma-7
-used in NASA Appollo program
-for real time simulations, and rocket guidance testing
1969 - Xerox buy Scientific Data Systems
-Pavlevsky gets $900M of Xerox stock (2, 166)
-Pavlevsky helps fund Intel as a venture capitalist (2, 210)
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1972 Dec 7 - Rolling Stone
-"Ready or not, computers are coming to the people.
-That's good news, maybe the best since psychedelics."
-Stewart Brand
Spacewar, Adventure @ Stanford AI Lab (2, 208)
PDP-10 $500K
- discrete transistors
-36 bit word
-mag core mem
-no IC's
-random access disk
-DEC tapes
-TOPS-10
-designed from the start to support interactive computing
-it was fun, addictive (2, 210)
-sometimes compared to VW Beetle - basic, simple, easy to understand
and work with
1972 - TOPS-10 (2, 208-210)
- developed by DEC in collaboration with MIT
-gave the feel of a personal computer
-"Our goal has always been that in a properly configured system, each
user has the feeling that he owns his portion of the machine for the time
he needs to use it." -- from the TOPS-10 manual (2, 209)
-user could work from a terminal
-create and manipulate files (xxxxxx.bas)
-Peripheral Interchange Program (PIP) move files to and from I/O equipment
-Text Editor and Corrector (TECO)
-Dynamic Debugging Tool (DDT)
Scientific Data Systems - Max Pavlevshy
SDS-940
-modified SDS 930
-modified by Berkley researchers funded by ARPA
Xerox PARC built their own PDP-10 clone called MAXC (Multiple Access
Xerox Computer
1975 - Xerox closes XDS Division (formerly SDS) (2, 167), misfit with PARC
Timesharing utilities
- similar to electric utilities
- had to be able to support peak loads
- leads to unused idle time
Computer Center Corp (C-Cubed) (2, 211)
-sells PDP-10 cycles in Seattle
-teenager Gates gets free time in exchange for helping debug the system
-folds in 1970
Resource One in SF (2, 211)
-partially funded by Whole Earth Catalog
-available to the public at free or low cost
-also failed
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