IBM 701
IBM 701, known as the "Defense calculator" while being developed, it was announced to the public on April 29, 1952, and was IBM's first commercial scientific computer. Its office computing siblings were the IBM 702 and the IBM 650. During the four years of production, 20 were sold. units.
Features
The system used Williams tubes for memory, consisting of 72 tubes with a capacity of 1024 bits, giving a total memory of 2048 words of 36 bits each. Each of the 72 tubes were 76 mm in diameter.
Memory could be expanded to a maximum of 4096 36-bit words by adding a second 72-tube system or by replacing the entire memory with magnetic core memory. The access time of the tube memory and the ferrite core memory was 12 microseconds. The tube memory needed to be "refreshed" periodically. An integer operation of addition took 5 12-microsecond machine cycles (60 microseconds), multiplied and divided into 38 12-microsecond machine cycles (456 microseconds).
Instructions and Data
The instructions were 18 bits long, single addressing.
- Sign (1 bit) - address of the whole word operating (-) or half word (+)
- Opcode (5 bits) - 32 instructions
- Address (12 bits) - 4096 half-word addresses
Numbers were either 36 bits or 18 bits long, sign, fixed point.
IBM 701 had only 2 registers accessible by the programmer:
- The accumulator was 38 bit long (assembling 2 bits of overflow).
- The multiplier/quotient had 36 bits of length.
Components
The IBM 701 system consisted of the following units:
- IBM 701 - Central Process Unit (CPU)
- IBM 706 - Electrostatic Storage Unit (2048 words in Williams tubes)
- IBM 711 - Perforated Card Reader (150 Tarj./min.)
- IBM 716 - Printer (150 Lines/min.)
- IBM 721 - Card Perforator (100 Tarj./min.)
- IBM 726 - Magnetic Belt Unit (39 Bits/cm)
- IBM 727 - Magnetic Belt Unit (78 Bits/cm)
- IBM 731 - Magnetic Tambor
- IBM 736 - Source of energy No. 1
- IBM 737 - Magnetic Nucles Unit (4096 words in memory of ferrite cores)
- IBM 740 - Departure Recorder for Cathodic Ray Tubes (CRT)
- IBM 741 - Power Source No. 2
- IBM 746 - Energy Distribution Unit
- IBM 753 - Magnetic Belt Control Unit (controlling up to ten IBM 727s)
Nineteen IBM 701 systems were installed. The University of California at Livermore developed a language with its build and runtime system for its IBM 701, called the "KOMPILER". IBM did not develop a FORTRAN compiler until the IBM 704.
The 701 can claim to be the first computer to demonstrate the potential of artificial intelligence with Arthur Samuel's game of Checkers.
The successor to the 701 was the register-equipped IBM 704, introduced 4 years after the 701; however, the 704 increased the instruction size from 18 bits to 36 bits to support the additional features.