Editing CDC 6600 (section)

==History and impact==
{{Main|Control Data Corporation}}
CDC's first products were based on the machines designed at [[Engineering Research Associates]] (ERA), which [[Seymour Cray]] had been asked to update after moving to CDC. After an experimental machine known as the ''Little Character'',<ref>{{cite web|title=Control Data Corporation, "Little Character" Prototype
|url=http://www.computerhistory.org/revolution/supercomputers/10/22/18|website=Computer History Museum|access-date=21 April 2016|ref=chm-little-character}}</ref> in 1960 they delivered the [[CDC 1604]], one of the first commercial [[Transistor computer|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{{When|date=May 2022}} 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".<ref>{{cite magazine |magazine=Personal Computer World |title=Seymour Cray: An Appreciation |first=Toby |last=Howard |date= February 1997 |url=http://www.cs.man.ac.uk/~toby/writing/PCW/cray.htm}}</ref>

Taking his core team to new offices near the original CDC headquarters, they started to experiment with higher quality versions of the "cheap" [[transistor]]s 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 3000 series|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 (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 laboratory wherever he wanted.

After a short search, Cray decided to return to his home town of [[Chippewa Falls, Wisconsin]], where he purchased a block of land and started up a new laboratory.{{When|date=May 2022}}

Although this process introduced a fairly lengthy delay in the design of his new machine, once in the new laboratory, without management interference, 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. The 6600 began to take form, with Cray working alongside [[James E. Thornton|Jim Thornton]], system architect and "hidden genius" of the 6600.

More than 100 CDC 6600s were sold over the machine's lifetime (1964 to 1969). Many of these went to various [[nuclear weapon]]-related laboratories, and quite a few found their way into university computing laboratories. A CDC 6600 was used to disprove [[Euler's_sum_of_powers_conjecture#Counterexamples|Euler's sum of powers conjecture]] in an early example of direct numerical search.<ref>{{cite journal |author1=L. J. Lander |author2=T. R. Parkin |title=Counterexample to Euler's conjecture on sums of like powers |journal=Bull. Amer. Math. Soc. |volume=72 |year=1966 |issue=6 |page=1079 |doi=10.1090/S0002-9904-1966-11654-3|doi-access=free }}</ref>

Cray immediately turned his attention to its replacement, this time setting a goal of ten times the performance of the 6600, delivered as the [[CDC 7600]]. The later{{When|date=May 2022}} [[CDC Cyber]] 70 and 170 computers were very similar to the CDC 6600 in overall design and were nearly completely backwards compatible.

The 6600 was three times faster than the previous record-holder, the [[IBM 7030 Stretch]]; this alarmed [[IBM]]. Then-CEO [[Thomas Watson Jr.]] wrote a memo to his employees on August 28, 1963: "Last week, Control Data&nbsp;... announced the 6600 system. I understand that in the laboratory developing the system there are only 34 people including the janitor. Of these, 14 are engineers and 4 are programmers&nbsp;... Contrasting this modest effort with our vast development activities, I fail to understand why we have lost our industry leadership position by letting someone else offer the world's most powerful computer." Cray's reply was sardonic: "It seems like Mr. Watson has answered his own question."<ref>{{cite book
|editor=Mark D. Hill
|editor2=Norman P. Jouppi
|editor2-link=Norman Jouppi
|editor3=Gurindar S. Sohi
|date=September 23, 1999
|title=Readings in Computer Architecture
|page=11
|publisher=Morgan Kaufmann
|isbn=978-1558605398}}</ref><ref>An exact image of the memo appears in: {{cite web |url=http://www.computerhistory.org/revolution/supercomputers/10/33/62	
|title=Watson Jr. memo about CDC 6600 |date=August 28, 1963}}</ref>