The Case For Biquinary

Keith R. Williams

Well, it may be that the 650-4 did use transistors. But if so, it doesn't seem to be noted anywhere. The 7070 is the first transistorized follow-up to the 650 that I have ever heard of.

The 650-4 may have been simply a modification of an existing product, not a "new" product. The IBM 650 RAMAC was an old product - the IBM 650 - hooked up to a new product - the RAMAC disk storage unit, and the RAMAC portion was transistorized.

If IBM did make a transistor 650, I would have expected it to be fairly prominently mentioned in histories of computing.

It is true there were transistor-based computers that used recirculating memory; the Packard-Bell 350 is an example. Thus, although drum memory is much slower than core memory, and the architectural changes of the 7070 were required when the shift to core memory was made, there is no a priori reason that IBM couldn't have converted the 650 to transistors, just as it did the 709, creating the 7090.

And we even have a precedent in their card equipment line to indicate that a transistorized 650 wouldn't have been called a 6500.

John Savard