IBM 701

IBM 701 belonged to the 700/7000 series of IBM in 1952 and came into the market. She was the first computer intended for scientific purposes by IBM. The versions for business customers were the IBM 650 and IBM 702 computer marks the transition to fully electronic computers at IBM.


There have been some partial electronic predecessor at IBM, the Automatic Sequence Controlled Calculator ( ASCC) of the 1940s and the Selective Sequence Electronic Calculator ( SSEC ) of 1948 ( with vacuum tubes and relays), but the 701 had only one quarter the size of SSEC and was 25 times faster.

A total of 19 systems were installed. Since most notably were customers from the U.S. defense complex, he was also called Defense Calculator. Expected had Thomas J. Watson only orders for five machines, which he expressed for example in the Shareholder Meeting in 1953 on the occasion of the introduction of the IBM 701 ( it may have originated the often Watson attributed, but probably wrong quote I think there is a world market for maybe five computers ). Before beginning production of the 701 he visited twenty potential customers and came back with 18 orders. Among other things, the Lawrence Livermore National Laboratory, University of California received a system. There is also a compiler has been developed, called compiler. IBM's own Fortran compiler did not come until 1954 with the IBM 704 to the market.

One of the leading developers were Nathaniel Rochester, Jerrier A. Haddad and Werner Buchholz at the head of the engineering department at IBM W. Wallace McDowell The design should stay as close as possible to the design of John von Neumann, as he approximately in the IAS - computer or the JOHNNIAC was realized.

There had to be competitors of the ERA in 1103 by Remington Rand, which was developed in secret for the NSA and in 1953 got permission marketed. The U.S. Defense Department led to both machines a benchmark test for numerical weather prediction through with a slight advantage for the IBM system.

On the 701 one of the first computer programs for Artificial Intelligence, a checkers program by Arthur Samuel ran. Also translation programs from the Russian ran in 1954 on the 701 's successor was the IBM 704, which was introduced in 1954 ( the business customer versions were the IBM 702, IBM 705).

System Description

  • Memory: electrostatic storage with 72 Williams tubes, which could store 1024 bits, corresponding to a memory of 2048 words, 36 bits each. The store was known as the IBM 706, the clock rate of the memory was 12 microseconds. The memory could be doubled by 72 more tubes ( to 4096 words). There was also drum memory and magnetic tape as a storage media (magnetic core memory only came in the era of successor ).
  • The instructions were 18 bits long with a single address. 33 different commands could be executed.
  • The numbers (which were binary coded internally ) were in fixed-point number format and 36 or 18 bit long signed integer.
  • The machine had two programmer accessible registers: an accumulator ( 38 bits with two overflow bits), and a multiply / divide register by 36 bits.
  • As input and output devices were punched card reader and printer, printers, input and output on magnetic tape ( IBM 726 tape drive ) or magnetic drum. In particular, the new magnetic tape readers contributed to the success of the IBM 701.