CDC 6600 - History and Impact

History and Impact

CDC's first products were based on the machines designed at ERA, which Seymour Cray had been asked to update after moving to CDC. After an experimental machine known as the Little Character, they delivered the CDC 1604, one of the first commercial transistor-based computers, and one of the fastest machines on the market. Management was delighted, and made plans for a new series of machines that were more tailored to business use; they would include instructions for character handling and record keeping for instance. Cray was not interested in such a project, and set himself the goal of producing a new machine that would be 50 times faster than the 1604. When asked to complete a detailed report on plans at one and five years into the future, he wrote back that his five year goal was "to produce the largest computer in the world", "largest" at that time being synonymous with "fastest", and that his one year plan was "to be one-fifth of the way".

Taking his core team to new offices nearby the original CDC headquarters, they started to experiment with higher quality versions of the "cheap" transistors Cray had used in the 1604. After much experimentation, they found that there was simply no way the germanium-based transistors could be run much faster than those used in the 1604. The "business machine" that management had originally wanted, now forming as the CDC 3000 series, pushed them about as far as they could go. Cray then decided the solution was to work with the then-new silicon-based transistors from Fairchild Semiconductor, which were just coming onto the market and offered dramatically improved switching performance.

During this period, CDC grew from a startup to a large company and Cray became increasingly frustrated with what he saw as ridiculous management requirements. Things became considerably more tense in 1962 when the new CDC 3600 started to near production quality, and appeared to be exactly what management wanted, when they wanted it. Cray eventually told CDC's CEO, William Norris that something had to change, or he would leave the company. Norris felt he was too important to lose, and gave Cray the green light to set up a new lab wherever he wanted.

After a short search, Cray decided to return to his home town of Chippewa Falls, WI, where he purchased a block of land and started up a new lab. Although this process introduced a fairly lengthy delay in the design of his new machine, once in the new lab things started to progress quickly. By this time, the new transistors were becoming quite reliable, and modules built with them tended to work properly on the first try. Working with Jim Thornton, who was the system architect and the 'hidden genius' behind the 6600, the machine soon took form.

More than 100 CDC 6600s were sold over the machine's lifetime. Many of these went to various nuclear bomb-related labs, and quite a few found their way into university computing labs. Cray immediately turned his attention to its replacement, this time setting a goal of 10 times the performance of the 6600, delivered as the CDC 7600. The later CDC Cyber 70 and 170 computers were very similar to the CDC 6600 in overall design.