CDC 8600

The CDC 8600 was the last of Seymour Cray's supercomputer designs while working for the Control Data Corporation. As the natural successor to the CDC 6600 and CDC 7600, the 8600 was intended to be about 10 times as fast as the 7600, already the fastest computer on the market.

Development started in 1968, shortly after the release of the 7600, but the project soon started to bog down. By 1971 CDC was having cash-flow problems and the design was still not coming together, prompting Cray to leave the company in 1972. The 8600 design effort was eventually cancelled in 1974, and Control Data moved on to the CDC STAR-100 series instead.

Design

In the 1960s computer design was based on mounting electronic components (transistors, resistors, etc.) on circuit boards. Several boards would be used to make a discrete logic element of the machine, known as a module. Overall machine cycle speed is strongly related to the signal path – the length of the wiring – requiring high-speed computers to make their modules as small as possible. This was at odds with the need to make the modules themselves more complex in order to increase functionality. By the late 1960s the individual components had stopped getting much smaller, so in order to increase the complexity of the machines, the modules would have to grow. In theory, this could slow the machine down due to signalling delays.