IBM 1620; was: Early Programming Books

Chuck Guzis cclist at
Mon Jun 21 14:52:36 CDT 2021

On 6/21/21 11:53 AM, Paul Koning wrote:

> Perhaps you were thinking about the CDC 6500 at the late lamented LCM?  That got some replacement stacks, which was an interesting puzzle because the read data connection out of the memory modules is a differential analog signal carrying the sense wire data, so the replacement module had to produce signals of that form.

No, it was definitely a CHM project--could have been for the 1401,
though.    In way of comparison to the 6000 core, 1401 and 1620 memory
is much larger, less dense and slower--and I don't believe that the
machine architecture makes use of a read-modify-write that the 6000 so
neatly exploited.

>From whence did the LCM 6500 come?


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