On Fri, 21 Aug 2009 20:05:24 +0200, Patrick Schaefer
<pa.schaefer@web.de> wrote:
Zero dB schrieb:
It did echo my characters with local echo off, so it definitely made
the round trip through the card.
That means cabling and level shifters work. Your first test (with IN#2)
proved that communication to the 6551 is possible as well. So now I
would swap crystal or UART. Swapping the 6551 is easy, but the crystal
requires soldering. You can try to connect a known-good part in
parallel, this works in 90% of the time.
In case you have a contact problem in the slot connector, as mentioned
elsewhere, the data read from the firmware EPROM would be corrupt as
well. If both $C200 and $C800 ranges look normal (the listing is in the
manual), your address and data lines are fine.
With a defective or missing firmware ROM ADT 1.21 will still work,
because this sofware does not use the PR#2/IN#2 routines.
Patrick
Patrick, Michael, everyone that has contributed:
You've been a great deal of help. Thanks so much.
I don't have a 6551 chip in that form factor to drop in, so I'm just
going to go on ebay and snag another card. They're going for about
20-25$ shipped, which isn't too shabby.
I'm going to check the $c200 and $c800 range output here before
ordering, but other peripherals work in slot 2 and the card contacts
are clean so I don't think the slot has anything to do with it. The
6551 or crystal is toast apparently.
Thanks again,