Bendix G-20
The Bendix G-20 computer was introduced in 1961 by the Bendix Corporation, Computer Division, Los Angeles, California. The G-20 followed the highly successful G-15 vacuum-tube computer. Bendix sold its computer division to Control Data Corporation in 1963, effectively terminating the G-20.
G-20
The G-20 weighed about 2,000 pounds (910 kg).[1]
The G-20 system was a general-purpose mainframe computer, constructed of transistorized modules and magnetic-core memory. Word size was 32 bits, plus parity. Up to 32k words of memory could be used. Single- and double-precision floating-point arithmetic were allowed, as well as a custom scaled format, called Pick-a-Point. A special form of the pick-a-point allowed an integer.
Memory locations 1 through 63 were used as index registers. The instruction set contained 110 instructions. The CPU included integral block I/O and interrupt facilities. Multiplication time was 51-63 microseconds and division time was 72-84 microseconds. The basic memory cycle time was 6 microseconds.
20-GATE
A special programming language, called 20-GATE,[2] was developed for the G-20.[3]
G-21 system
A special configuration of the G-20, a dual-processor G-21, was used to support campus computing at
Another feature of the G-21 system was its high-speed Philco "Scopes" system - when
The directory system was called AND - Alpha Numeric Directory. Teleprocessing users could store programs on disks, tapes, or the RCA RACE mass storage unit interfaced through an RCA 301 computer. Users could retrieve and edit programs through AND. The 1-inch magnetic tapes were block addressable, allowing AND to manage a directory file system interchangeably on any available magnetic storage (tape, disk, or RACE cards).
The machine was programmed in a dialect of ALGOL-60 called ALGOL-20. Deviations from Algol-60 included the lack of support for recursion, extensions to embedded G-20 machine language within ALGOL - WHAT, and a CIT-developed printer formatting language. Another language was GATE - the General Algebraic Translator Extended. It also used IPL-V (Newell's Information Processing Language-5) and Linear IPL-V as well as COMIT, and the assembler THAT. MONITOR was the supervisory program, and the special set of routines was called THEM THINGS.
An exposition of the G-21 design appears in a Carnegie Mellon webcast by the designer, Jesse Quatse, at CMU CS50. [1]
Equipment list, circa 1965/66
- CC-11 Real time clock and auxiliary console
- CP-11 Central Processor (2)
- MM-10 Memory Module (1)
- MM-11 Memory Module (7)
- MM-12 Memory Module, modified to work with display system
- DM-11 Disk unit
- TC-10 Tape Control Unit (2)
- MT-10 Magnetic Tape Unit, used 1" tape (8)
- PT-10 Paper Tape Unit
- SE-10 Teletype buffer
- LP-12 high speed line printer (2)
- LP-10 low speed line printer
- 3 display consoles, and 1 display controller.
- An IBM 1402 card reader/punch was used for batch job submission.
References
Notes
- ^ "COMPUTERS AND DATA PROCESSORS, NORTH AMERICA: 2. Bendix Computer Div. of Bendix Aviation, G-20, Los Angeles, Calif". Digital Computer Newsletter. 12 (2): 1–6. Apr 1960.
- ^ General Algebraic Translator Extended
- ^ "20-GATE: Algebraic Compiler for the Bendix G-20", Carnegie Tech Computation Center, September 1962.
Bibliography
- Anecdotes, Jesse T. Quatse, IEEE Annals of the History of Computing, vol. 28, no. 3, pp. 76–80, Jul-Sept, 2006
- A Visual Display System Suitable for Time Shared Use, Jesse Quatse, revised, 1966
- Design of the G-21 Multi-Processor System, Jesse Quatse, 1965
- Interactive Programming at Carnegie Tech, A H Bond, 1968 [2]
- THAT - A Language Manual, CIT Computer Center Programming Staff, 1965 [3]
- WHAT, James Moore, CIT Computer Center, 1965 [4]
- The Bendix G-20 Central Processor Machine Language, 1961, [5]
- The Bendix G-20 Peripheral Equipment Machine Language, 1961, [6]
- The Bendix G-20 General Reference Manual, 1962, [7]