RE: blue wire fix on flat C-128...

From: Bil Herd <>
Date: Fri, 29 Oct 2010 15:41:31 -0400
Message-ID: <>
That wire is there because that rev of the PCB ended up with a stub PCB
trace on A10 when the Z80 was the active processor.

Basically the symptom was that CPM wouldn't load reliably with that rev of
the board, after we had fixed a few of the other issues.  If you scoped it
just right you could see a reflection "stand" right in the wrong place.

The back story was I was fighting with my boss about something, I had been
working 20 hour days for months and was getting a little tired, he said
something, and my response was fine, have someone else fix the cpm
problem.  I spent the week relaxing, SLEEPING and getting caught up on my
paperwork while all of the "extra" engineers we tended to carry were
ordered to fix the new problem, I am sure it was meant to be a lesson that
we animals were not all that important after all.

At the end of the week my boss, Joe, walked into my office and said one
sentence "fix it or your fired".   I just grinned as I did love a
challenge back then. Took me about an hour to find the standing wave, I
couldn't fault the layout guy as he had performed a minor miracle in
getting that thing laid out to the constraints (had to be D compatible,
both American and Japanese autoinsert compatible which was a first, and
real tight congestion near the hole in the board and a silly manager had
wasted the first 5 days of the 7 we had scheduked).  I applied a wire to
the PCB much like on the systems today and the signal cleaned right up,
basically it creates a loop and you cant reflect off the end when there is
no end. I never dreamed that it would be there even a few months later but
we never had a reason to rev the board beyond just that wire I guess.

My boss was extremely skeptical to say the least, given that everyone had
tried all week long and I said it just needed a redundant wire.  We did a
"baby" run of 10,000 units over the weekend to prove that it really did
fix it, sadly the engineers who tried all week to fix it were forced into
weekend duty as assemblers and testers.

There was one other part of the story that became the vernacular around
cbm; one of the technicians named Curt ("Chip", aka "Arlo") was getting
steadily drunk while manning the line on Sunday and got in an argument
with one of the engineers  that got stuck with the weekend duty.  This
engineer (named Kong) didn't know what we animals knew which is it's
useless to argue with Arlo when he's drunk, especially when he has a
soldering iron in his hand while he's drunk.  Finally Arlo holds out both
hands like he is holding a pumpkin or a large tree trunk and says in a
loud voice "Blow me Kong!" Arlo's girlfriend looks at the size of the
imaginary treetrunk/pumpkin he is holding out, and based on personal
experience, noted for everyone that his member was nowhere near the size
he was proclaiming it to be, again we were talking large treetrunk. By
this time everyone is rolling and production pretty much stopped.

From that time on, whenever someone got irritated or wanted the last word
or the last laugh they would hold out an imaginary treetrunk and proclaim
"Blow me Kong!"   lol... I remember a year later hearing this resonate
from the second floor of the bar we hang out at (course no one there knew
what a Kong was)....

 Hey you wanted the white wire story.....

Bil Herd
-----Original Message-----
[] On Behalf Of Gene Buckle
Sent: Friday, October 29, 2010 9:44 AM
Subject: blue wire fix on flat C-128...

Every flat C-128 I've opened up has a blue-wire fix on the board (It's
actually a white wire..;) ) - what issue was this wire intended to



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Received on 2010-10-29 19:41:31

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