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The 1130's Technology

Little about the 1130's technology was new or unique; the one exception was its inexpensive disk storage.

The cartridge-based "Ramkit" disk drive was developed by IBM; the cartridge design was later used by many other companies, including Digital Equipment Corporation in their RK05. It provided 500KW random-access storage, making previously infeasible tasks manageable. In 1131 models including a disk drive, it was mounted above the power supply in the right-hand cabinet. For users who required more disk storage, up to three additional drives could be attached to the system through the 1131 Storage Access Channel option.

The system's other building blocks (SLT modules, core memory, the Selectric console printer, and the various peripheral devices) were all taken from other systems, pieced together for maximum price/performance.

SLT (Solid Logic Technology) circuitry, developed for the System/360, is the basis for the 1131 CPU. For these circuits, IBM developed a method of densely packing individual transistors, diodes, and other circuit components on a small ceramic plate, rather than relying on the new and unproven monolithic integrated circuit technology that was just emerging at the time. Individual transistor and diode dice were placed upside down on the ceramic substrate onto tiny solder balls, and the assembly was heated to melt the solder. The 1131 CPU is built from an array of small plug-in circuit boards, each holding typically four or five discrete resistors or capacitors and four to eight half-inch square metal cans containing SLT circuits.

Core memory was the highest-performance memory device available when the 1130 was introduced. Another benefit for IBM was that the company had developed highly efficient production techniques for producing it, and its profit margins were enormous.

Punched cards, of course, were IBM's best known innovation. A massive infrastructure was in place to work with them, and the 1130 leveraged that.