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

Al Kossow aek at bitsavers.org
Mon Sep 5 10:55:55 CDT 2016

This is why Alto restoration with one set of boards is extremely difficult.
The machine wasn't designed to be serviced. Almost everything has to work
before you can do anything, and there is a very high probability that in the
process of bringing it up you will corrupt the disk pack. Hopefully the ethernet
bridge boards will come through soon so you can try to etherboot a diagnostic
once you stop getting parity errors. The ECC memory subsystem is fairly complicated
so it wouldn't surprise me there is a problem with it. You might try reducing the
number of installed memory boards. If you can get it to the point where it hits the
disk it should sequentially read a bunch of tracks, seek to zero, then start to boot
which changes the pitch of the 5v switching supply. You can tell a lot about what's
going on just by the sound of the power supply. If the power supply isn't chirping
the machine isn't doing much.

On 9/3/16 11:08 PM, curiousmarc3 at gmail.com wrote:
> Episode 5, still does not boot, but we are starting to follow long why:
> https://youtu.be/Wr7vDZpniNIr

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