Y Combinator is restoring one of Alan Kay's Xerox Alto machines

Josh Dersch derschjo at gmail.com
Fri Sep 9 03:29:22 CDT 2016

On 9/9/16 1:15 AM, curiousmarc3 at gmail.com wrote:

>> On Sep 7, 2016, at 4:18 PM, Josh Dersch <derschjo at gmail.com> wrote:
>> Yep, the NEC uPD416D's are what we have in the Alto we recently restored.
>> And yeah, it takes awhile, but it's worth the effort :).
>> Have fun!
>> - Josh
> Out of curiosity, did you find any bad RAM chips in your system? If so, how many? I had only one bad one in one of my HP 85 (out of 8), but it definitely happens.
> Marc

Yes, there were two, if I recall correctly.  And while swapping memory 
chips out for testing, I found one with a bent-over pin that had likely 
been that way since it was installed in the 70s.  It apparently worked 
(at least back in the day -- it made contact with the pin in the socket) 
but I decided to fix it anyway.  We found several other ICs in the 
system that had similarly bent pins, some of which were causing 
intermittent problems.

In daily use at the LCM, we have had several RAM chips in our Altos 
fail.  Fortunately, the DMT (Diagnostic Memory Test) that runs when the 
system goes idle finds them pretty quickly (and tells you where the bad 
chip is, too...)

- Josh

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