The iconic IBM System/360 released 55 years ago #IBM #VintageComputing #Mainframes @IBM

Via Ken Shirriff: The revolutionary IBM System/360 computers were announced 55 years ago today (April 7th). These mainframes ruled the computing industry for years. Their iconic consoles, covered with lights and switches, showed internal state.

IBM S/360 Model 30 on display at the Computer History Museum.
IBM S/360 Model 30 on display at the Computer History Museum.

Ken’s excellent article goes into great detail on these exceptional machines.

The IBM System/360 was a groundbreaking family of mainframe computers announced on April 7, 1964. Designing the System/360 was an extremely risky “bet-the-company” project for IBM, costing over $5 billion. Although the project ran into severe problems, especially with the software, it was a huge success, one of the top three business accomplishments of all time. System/360 set the direction of the computer industry for decades and popularized features such as the byte, 32-bit words, microcode, and standardized interfaces. The S/360 architecture was so successful that it is still supported by IBM’s latest z/Architecture mainframes, 55 years later.

Prior to the System/360, IBM (like most computer manufacturers) produced multiple computers with entirely incompatible architectures. The System/360, on the other hand, was a complete line of computers sharing a single architecture. The fastest model in the original lineup was 50 times as powerful as the slowest, but they could all run the same software. The general-purpose System/360 handled business and scientific applications and its name symbolized “360 degrees to cover the entire circle of possible uses.”

Large computer room with an IBM System/360 Model 85. The CPU, the double-H unit in the center, weighed over 7 tons.Cabinets in front are core memory storage, holding 256 kilobytes each.
Cabinets on the right are I/O channels, connected to I/O devices at the back:
tape drives, printers, disk drives, and card readers. Photo from IBM.
Large computer room with an IBM System/360 Model 85. The CPU, the double-H unit in the center, weighed over 7 tons. Cabinets in front are core memory storage, holding 256 kilobytes each. Cabinets on the right are I/O channels, connected to I/O devices at the back: tape drives, printers, disk drives, and card readers. Photo from IBM.

Read the extensive history of the 360 in Ken’s article here.

Console for the IBM System/360 Model 85 at NSA (source).
Console for the IBM System/360 Model 85 at NSA (source).

Did you use a System/360? Ed: I think my first programming was on a System/370 Let us know your experiences in the comments below.


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2 Comments

  1. System 360 (now called zOS) mainframes are still in wide use in financial industries. We still use them at my employer for much of our work during the trading day, since they provide a level of reliability for simultaneous transactions that can’t be matched. We then use the processing power to calculate all of the net trades and reconcile everything with other market participants overnight.

    Fun fact. The System 360 was introduced to the American public at the NY World’s Fair in 1964. The Raspberry Pi was introduced to the American public at NY Maker Faire in the same spot. Both had similar specs.

  2. Yup. When I was in high school in Springfield, MA, the local community college rented a 360\40 to support remote an APL terminals in each of Springfield’s public high schools and some of the junior high schools. They wound up unable to support the rent, and so replaced it with a 360\25 which would not support the remote terminals. Those of us that wished could go to the Springfield Technical Institute (later STCC) computer lab and use the computer there. I thus learned Fortran IV, Cobol, and OS 360 Assembler, along with the necessary job control language (JCL) to control the running of the punched card decks.
    Not many people still alive know how to edit cards on a keypunch – adding or removing characters took some manual skill holding one card in place while advancing the other in “duplicate” mode.

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