G3 (computer)

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The G3 in 1966 with an operator typewriter in the middle, screen on the right and magnetic tape recorders and punched tape readers on the left

The Electronic Calculating Machine G3 or shortly G3 was under the direction of physicist Heinz Billing in the Max Planck Institute for Physics constructed and built as a single piece computer and was operated there from 1960 to 1972.

history

The G3 was the successor to the G1 and G2 and named after Göttingen , the seat of the Max Planck Institute for Physics until it was moved to Munich in 1958.

The starting point for the development of the G1 to G3 was formed by practical problems in the field of theoretical physics and astrophysics, because of which Ludwig Biermann , head of the astrophysical department, pushed forward the project of an automatic program-controlled digital calculating machine ( G1 ) from 1949 .

Preliminary work and planning for the G3 began in 1953, the actual development in early 1955 at the same time as the G2 went into operation and its construction in autumn 1956. When the G1 moved to Munich in 1958, the G1 went out of service; the G2 and G3 were dismantled and reassembled in Munich.

The G3 was inaugurated in December 1960 in the department laboratory at the new Munich location. Because of its great reliability from the start and its ease of use, the G2 was hardly used afterwards , so that it was replaced in September 1961 in the main building of the Max Planck Institute. The G3 was later supplemented with magnetic tape recorders and a black and white screen for outputting curves.

Over the years, the G3 increasingly faced competition from commercial large-scale computer systems in the Garching data center, such as the IBM 7090 (1962) and its successor there, the IBM 360/91 (1967).

On November 9, 1972, Heinz Billing took the G3 out of service during a ceremony.

architecture

Close-up view with various calculation registers on the right and input / output controls on the left
As flip-flop -connected double triodes in replacement attachment, a number between glow lamps for status indication
Detail of the tube assembly: At the top parts of registers, each bit with a double triode for storage and a glow lamp for display; bottom middle power pentodes for direct control of the printer

Like the G1 and G2 , the G3 was designed using tube technology, which enabled a higher switching speed than the transistors available at the time ; so the registers were made up of bistable tube circuits, a flip-flop for each bit .

Unlike its predecessor, however, it had a parallel, microprogram- controlled arithmetic unit : The bits of a number were e.g. B. not (serially) one after the other, but (in parallel) at the same time, and the individual arithmetic commands, such as multiplication or root extraction, consisted of elementary operations such as shifting the number in the arithmetic register, adding one register content to another, etc. Thanks to the microprogram control one could also Implement further machine commands with technically simple means that were not intended from the start, even after the G3 has been commissioned .

A self-developed magnetic core memory was used as the main memory instead of the previous drum memory .

At the suggestion of Friedrich L. Bauer and Klaus Samelson one was stack (stack) in the form of 16 reserved memory words and corresponding machine instructions implemented.

These innovations made the G3 a fast calculator.

Technical specifications

  • Mode of operation: parallel micro-commands controlled by a ferrite core chain, clock frequency 200 kHz, 6 index registers for address modification, 16 basement registers for intermediate storage
  • Information representation: word length 43 bits, number system: dual, number range 10 −77 <| x | <10 77 , floating point 33 bits mantissa, 9 bits exponent, 1 bit identifier
  • Commands: 64 one-address commands, 2 commands of 21 bits per word
  • Main memory: core memory 4,096 words à 42 bits + 1 identifier bit, cycle time: 10 µsec
  • Computation times : floating point multiplication 300–400 µsec, average operation speed 5,000–10,000 op / sec
  • Input / output: 10 punched tape readers (200 cps / sec), typewriter (13 cps / sec), tape punch (50 cps / sec), line printer, cathode ray display device as analog output (from 1962), magnetic tape storage (from 1961)
  • Components: 1,500 tubes, 6,000 germanium diodes, 600 to 700 ferrite cores for the microprogram control, 176,128 ferrite cores for the main memory

programming

The programs for the G3 were developed in a machine-oriented symbolic language, coded on programming paper and punched into punched tape using a modified typewriter. The G3's "reading program" read in the punched tape, assembled a machine program from it, loaded it into the working memory and then started it.

literature

Web links

Commons : G3 (computer)  - collection of images, videos and audio files

Individual evidence

  1. ↑ Heinz Billing : Back and forth to G1 to G3 (excerpt) (PDF) In: GWDG report no.69 . Society for scientific data processing mbH Göttingen (GWDG). 2006. Retrieved July 18, 2019.
  2. ↑ Manfred Eyßell: Heinz Billing - the builder of the first German electronic computer (Part 1) (PDF) In: GWDG -Nachrichten 4/2010 . Society for scientific data processing mbH Göttingen (GWDG). P. 12 ff. 2010. Accessed July 7, 2019.
  3. ↑ Manfred Eyßell: Heinz Billing - the builder of the first German electronic computer (Part 2) (PDF) In: GWDG -Nachrichten 5/2010 . Society for scientific data processing mbH Göttingen (GWDG). S. 17. 2010. Accessed July 7, 2019.
  4. ↑ a b ibid. P. 19
  5. ↑ a b ibid. P. 21
  6. ↑ a b ibid. P. 27
  7. ↑ ibid. P. 22
  8. ↑ ibid. P. 25
  9. ↑ ibid. P. 24