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Specialty Expressions: IBM 704

ExpressionsDomainDefinition
IBM 704ComputingIBM 704 A large, scientific computer made by IBM and used by the largest commercial, government and educational institutions. The IBM 704 had 36-bit memory words, 15-bit addresses and instructions with one address. A few index register instructions had the infamous 15-bit decrement field in addition to the 15-bit address. The 704, and IBM 709 which had the same basic architecture, represented a substantial step forward from the IBM 650's magnetic drum storage as they provided random access at electronic speed to core storage, typically 32k words of 36 bits each. [Or did the 704 actually come *before* the 650?] A typical 700 series installation would be in a specially built room of perhaps 1000 to 2000 square feet, with cables running under a raised floor and substantial air conditioning. There might be up to eight magnetic tape transports, each about 3 x 3 x 6 feet, on one or two "channels." The 1/2 inch tape had seven tracks and moved at 150 inches per second, giving a read/write speed of 15,000 six bit characters (plus parity) per second. In the center would be the operator's console consisting of cabinets and tables for storage of tapes and boxes of cards; and a card reader, a card punch, and a line printer, each perhaps 4 x 4 x 5 feet in dimension. Small jobs could be entered via punched cards at the console, but as a rule the user jobs were transferred from cards to magnetic tape by off-line equipment and only control information was entered at the console (see SPOOL). Before each job, the operating system was loaded from a read-only system tape (because the system in core could have been corrupted by the previous user), and then the user's program, in the form of card images on the input tape, would be run. Program output would be written to another tape (typically on another channel) for printing off-line. Well run installations would transfer the user's cards to tape, run the job, and print the output tape with a turnaround time of one to four hours. The processing unit typically occupied a position symmetric but opposite the operator's console. Physically the largest of the units, it included a glass enclosure a few feet in dimension in which could be seen the "core" about one foot on each side. The 36-bit word could hold two 18-bit addresses called the "Contents of the Address Register" (CAR) and the "Contents of the Decrement Register" (CDR). On the opposite side of the floor from the tape drives and operator's console would be a desk and bookshelves for the ever-present (24 hours a day) "field engineer" dressed in, you guessed it, a gray flannel suit and tie. The maintenance of the many thousands of vacuum tubes, each with limited lifetime, and the cleaning, lubrication, and adjustment of mechanical equipment, was augmented by a constant flow of bug reports, change orders to both hardware and software, and hand-holding for worried users. The 704 was oriented toward scientific work and included floating point hardware and the first Fortran implementation. Its hardware was the basis for the requirement in some programming languages that loops must be executed at least once. The IBM 705 was the business counterpart of the 704. The 705 was a decimal machine with a circular register which could hold several variables (numbers, values) at the same time. Very few 700 series computers remained in service by 1965, but the IBM 7090, using transistors but similar in logical structure, remained an important machine until the production of the earliest integrated circuits. [Was the 704 scientific, business or general purpose? Difference between 704 and 709?] (1996-01-24). Source: The Free On-line Dictionary of Computing..

Source: compiled by the editor from various references; see credits.

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Extended Definition: IBM 704

IBM 704

An IBM 704 mainframe (image courtesy of LLNL)
An IBM 704 mainframe (image courtesy of LLNL)

The IBM 704,[1] the first mass-produced computer with floating point arithmetic hardware, was introduced by IBM in April, 1954. The 704 was significantly improved over the IBM 701 in terms of architecture as well as implementation, and was not compatible with its predecessor.

Changes from the 701 included the use of core memory (instead of Williams tubes) and addition of three index registers. To support these new features, the instructions were expanded to use the full 36-bit word. The new instruction set became the base for the IBM 700/7000 series scientific computers.

To quote the IBM 704 Manual of operation (see external links below):

The type 704 Electronic Data-Processing Machine is a large-scale,
high-speed electronic calculator controlled by an internally stored
program of the single address type.

IBM stated that the device was capable of executing up to 40,000 instructions per second. IBM sold 123 type 704 systems from 1955 to 1960.

The programming languages FORTRAN and LISP were first developed for the 704, as was MUSIC, the first computer music program by Max Mathews.

In 1962 physicist John Larry Kelly, Jr created one of the most famous moments in the history of Bell Labs by using an IBM 704 computer to synthesize speech. Kelly's voice recorder synthesizer vocoder recreated the song Daisy Bell, with musical accompaniment from Max Mathews. Arthur C. Clarke of 2001: A Space Odyssey fame was coincidentally visiting friend and colleague John Pierce at the Bell Labs Murray Hill facility at the time of this remarkable speech synthesis demonstration and was so impressed that he used it in the climactic scene of his novel and screenplay for 2001: A Space Odyssey,[2] where the HAL 9000 computer sings the same song.[3]

Ed Thorp also used the IBM 704 as a research tool, investigating the probabilities of winning while developing his blackjack gaming theory.[4][5] He used Fortran to formulate the equations of his research model.

The IBM 704 was used as the official tracker for the Smithsonian Astrophysical Observatory Operation Moonwatch in the fall of 1957. See The M.I.T. Computation Center and Operation Moonwatch. IBM provided four staff scientists to aid Smithsonian Astrophysical Observatory scientists and mathematicians in the calculation of satellite orbits: Dr. Giampiero Rossoni, Satellite Coordinator of IBM Applied Science (Cambridge), Dr. John Greenstadt, Thomas Apple and Richard Hatch.

Instruction and data formats

The basic instruction format was a 3-bit prefix, 15-bit decrement, 3-bit tag, and 15-bit address. The prefix field specified the class of instruction. The decrement field often contained an immediate operand to modify the results of the operation, or was used to further define the instruction type. The three bits of the tag specified any combination of three "decrement registers", an early kind of index registers in which the contents of the registers were subtracted from the address to produce an effective address. The address field either contained an address or an immediate operand.

  • Fixed point numbers were stored in binary sign/magnitude format.
  • Single precision floating point numbers had a magnitude sign, an 8-bit excess-128 exponent and a 29 bit magnitude
  • Alphanumeric characters were 6-bit BCD, packed six to a word.

References

  1. 704 photos from IBM
  2. Arthur C. Clarke online Biography
  3. Bell Labs: Where "HAL" First Spoke (Bell Labs Speech Synthesis website)
  4. Discovery channel documentary with interviews by Ed and Vivian Thorp
  5. The Tech (MIT) "Thorpe, 704 Beat Blackjack" Vol. 81 No. I Cambridge, Mass., Friday, February 10, 1961

Further reading

  • Charles J. Bashe, Lyle R. Johnson, John H. Palmer, Emerson W. Pugh, IBM's Early Computers (MIT Press, Cambridge, 1986)
  • Steven Levy, Hackers: Heroes of the Computer Revolution

External links

Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "IBM 704". Image Credit.