> On Jun 21, 2021, at 3:52 PM, Chuck Guzis <ccl...@sydex.com> wrote:
>
> 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?
>
> --Chuck
Some vague memory says Purdue. LCM actually got it running, which was an
interesting problem. It required recreating the inter-chassis cables (since
the original ones were cut as part of dismantling the machine) and restoring
the cooling system. That was a bit tricky since it uses non-PC coolant, which
actually still exists but can't be manufactured any longer -- you have to use
whatever recycled material still exists in the world, and find a graybeard AC
tech who knows how to work with the stuff.
I think the machine is pretty much original except that a few core stacks were
busted so they were replaced by RAM based emulations. And it may be that the
original console display wasn't used because of worries of breaking it -- the
design of that machine wasn't very good and it apparently has reliability
issues.
paul
