Problems with computer

[Tim Vanderhoek <vanderh@ecf.utoronto.ca>]

Okay, guys, first, as I've already said, I'm really sorry the computer
didn't work when we actually needed it to show the TA.

However, as promised, I debugged the board, and I think I've found the
problem.

When you power-on the comp board, all input pins are randomly set to
be either high or low.

(Late!) last night, I added an on/off switch to Qubit, as per earlier
discussions with Joyce.  I completely forgot about the on/off switch
during our mini-presentation.  Presumably the input pin associated
with the on/off switch was getting set to off (== low) and, as a
result, Qubit wouldn't run.  This is also why it probably worked
erratically (given random chance, the input pins seem to have a
somewhat higher chance of being randomly set to low than randomly set
to high).

I'm really sorry I let this happen, especially given how stupid it is.
The worst part is, as soon as I set it down on my desk at home and ran
the Qubit eprom, I remembered about the on/off switch.

However, this does highlight something: I really really really need to
have the circuit board connections soldered together with appropriate
connectors (not alligator clips!).  This wouldn't have happened if a
complete power distribution system had been in place since the on/off
pin would have been pulled to the correct value (I'm not trying to
blame anyone --- this is my fault for completely forgetting I added an
on/off switch).  But please, I have spent literally hours and hours
chasing down apparent problems (typically turning-out to be non-problems) 
that could have been avoided by a completely finished and connected
power and information-distribution system.  If I could do tests that
required no alligator clips at all (except for two to connect to the
motor battery supply), I would be very very happy indeed.

That said!  I look forward to working on Zeta again Saturday morning!
I'm sure we'll solve whatever problems arise!  See you then!!  :-)


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Signature withheld by request of author.