From: Bryan Pope (bpope_at_wordstock.com)
Date: 2007-03-21 00:50:08
And thusly were the wise words spake by ruud.baltissen@abp.nl
>
> > Is there a webpage that describes how to measure the I/O signals?
>
> Have a look at the NRFD (Not Ready For Data) signal first. This signal
> tells the computer that the drive is not able to receive data at all at
> this moment. So have a look at this signal first: (L) means active and
> the computer will wait until it is (H). So if it is (L) indeed, check
> the level all the way up to the I/O ICs in both the drive and computer.
>
Ruud,
A logic probe is also in my order from Jameco. Once I get that
(next week) I will check what you said.
> I read you replaced a 6522. In the drive or the computer? I had a
> similar case and here the troubleshooter was the 6522 in the computer.
>
It was in the drive, from another working one. I was going
by the 2031 troubleshooting guide on zimmers.net which said if it
locks up while loading check the IEEE interface components and the
ROM. Another section (page-12l) titled "IEEE Interface" says all
of the signals are controlled by device U3H (the 6522 I tried
swapping) plus U1S (75160) and U1A (75161). Hopefully I was
going in the right direction!
Thanks!,
Bryan
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