On 2/7/2012 12:42 PM, David Forbes wrote:
Another dual triode that was common as dirt in computers was the 6211. It's faster than the 5963. IBM bought millions of 'em from GE 50 to 55 years ago.
Oops, they're not quite a 12AU7. To quote from the IBM 650 computer's descriptive paper presented to the ACM in 1954,
"Approximately 2000 tubes are used in the machine. They are the 5965, 6211, 12AY7, 6AL5, 2D21 and 5687. Types 6211 and 5965 are similar to the 12AV7. These are used because they meet special IBM acceptance tests."
I have some other books at home with more information on the development of these special digital tubes. As I recall, it was a complete mystery why the tubes failed in service, the problems being ascribed to black magic until the chemists sorted it out.
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