ExpandaCore 18 core memory

Camiel Vanderhoeven iamcamiel at gmail.com
Mon Jul 25 07:37:54 CDT 2016

Op 25 jul. 2016 2:25 p.m. schreef "Göran Axelsson" <axelsson at acc.umu.se>:
> My guess so far is that there is a problem with reading and writing to
the memory. The problem is that I have no documentation over the memory
module except a drawing of the circuitry used to access it. ND bought
several different models of core memory for it's early computers and just
adapted the interface.
> So once again I turn to the cctech for help, does anybody have
instructions about ExpandaCore 18 from by Cambridge Memories INC, Newton,
Massachusetts (also known as CMI but probably not the CMI on bitsavers).
> So far the only thing I've found was a newsflash in a computer magazine
about a sale of memories to another computer maker.

I can't help you with that, but is it just the core stack itself you don't
have docs for, or does the CMI part include some driver circuitry? If it's
just the stack, you should be able to do without docs for that. Core memory
doesn't go bad unless it's physically damaged. If it is physically damaged,
repair can be very difficult, depending on the diameter of the cores.

How are you troubleshooting this? Can you deposit a value in memory from
the front panel, then read it back? If that works, but one or more bits are
off, there's a good reason to look at the core driver circuitry. If it
doesn't work at all, the problem could be anywhere. Try hooking a logic
analyzer to the address and data lines, clock, and read/write control lines
for a start.

Good luck!


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