Stupid problems / was Re: Further 11/40 unibus questions...
dkelvey at hotmail.com
Tue Jun 9 08:39:56 CDT 2009
> From: lists at databasics.us
> Brent Hilpert wrote:
>> I suffered with the problem for ages, then finally clued in that my bench/lab
>> power supply - which of course contained a power transformer which of course
>> would generate a magnetic field - was sitting on top of the scope, just above
>> the CRT.
> Back in the old days, I got a call from a friend who was being driven
> nuts by his CP/M computer, which was a current, nice machine at the
> time. His 8" disks were randomly flaking out on him, and he had taken
> the whole system in to the store several times (a difficult task, back
> then) and when they set it up, there were no problems. He was going
> crazy, keeping multiple backups of each session, and still losing a lot
> of work. He had had numerous people over after business hours to try to
> find the problem, but had had no luck. With a techie there, there was
> never a problem.
> I went over to his place, and we watched for a while, with no effect. I
> wrote a program which wrote pseudo-random crap on the disk, and then
> randomly skipped around reading various tracks and sectors, checking the
> data, and then re-writing it, ringing the bell like a hunchback on crack
> if it found one of the sectors did not have the proper information or if
> a write failed. (Program: Quasi.com)
> We ran that sucker for hours, with no problems detected. I told him
> that my wife and I had plans for dinner that I didn't want to mess with,
> so when she called, that was it, I had to leave. It was getting near
> the time when she would call, and he was getting desperate. He appeared
> to be close to tears with frustration. "Look, I know there's no problem
> NOW, but, really, it fails all the time when I'm doing actual work.
> What's different about that?" Whiner.
> Finally, as things happen, my time was up -- my wife called.... And the
> terminal bell started going nuts at the same time. We both started, and
> I reached to pick up the phone.... which was sitting on top of his disk
> drive enclosure. The (Old Bell System) phone had a real bell, and the
> magnetic field generated when the phone rang was scrambling any disks in
> the drive at the time. During work, of course, he got lots of calls,
> hence had lots of problems. After work, nobody called. Sheesh. I
> moved his phone to the other side of the desk... problem solved.
I'd seen similar problems from setting the video monitor on
top of the PC. The color screens had the de-guassing coil
that came on when turned on. It would get the disk to.
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