Re: SSC Failure - odd symptoms

[Zero dB <no@email.com>]

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, 
Jayson