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

CuriousMarc curiousmarc3 at gmail.com
Wed Sep 7 17:43:30 CDT 2016

> > On Sep 5, 2016, at 9:30 AM, Josh Dersch <derschjo at gmail.com> wrote:
> >
> > At the LCM, I used an Apple II to test out the Alto's memory -- the 
> > Alto II XM uses 4116 RAM chips.  I swapped in a row at a time and wrote
> > little BASIC program to test for obvious errors.  This was 
> > time-consuming, but eliminated the obviously bad chips, which helped
> Oh, that's so simple and clever! Are these 16k chips? I don't have an
Apple II,
> but I wonder if I could use the same trick and plug them in my HP 85 
> for which I just managed to burn the service ROM, which has a memory 
> test built in.

I checked, and the mysterious HP 1818-1396 or 1818-0341 RAM chips used in
the HP-85 appear to be NEC uPD416-2 or MOSTEK 16k chips. They appear to be
pin for pin, voltage and speed compatible with the MOSTEK 4116-3 used in the
Alto. So it looks like I could check the Alto Xerox II-XM RAM chips on my
8 at a time, that might take a while :-). Thanks for the tip, I'd never have
thought about it!

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