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----- From: owner-cbm-hackers@musoftware.de [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Gene Buckle Sent: Friday, October 29, 2010 9:44 AM To: cbm-hackers@musoftware.de 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 address? tnx. g. -- Proud owner of F-15C 80-0007 http://www.f15sim.com - The only one of its kind. http://www.simpits.org/geneb - The Me-109F/X Project ScarletDME - The red hot Data Management Environment A Multi-Value database for the masses, not the classes. http://www.scarletdme.org - Get it _today_! Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end. Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2010-10-29 19:41:31
Archive generated by hypermail 2.2.0.