8251 troubles

[dwight elvey]

Hi
 I could send to the video. It is a Poly88. I've been working
on getting my images transferred. I thought the serial
would be easy. Ha ha ha.
 I don't have another chip handy but can get one tomorrow.
I can alway send directly to video RAM. That is similar to the
led port.
Thanks for the sanity check.
Dwight


> From: thrashbarg at kaput.homeunix.org
>
> On Sun, 2008-04-27 at 09:24 -0700, dwight elvey wrote:
> -- snip --
>> TIN:
>> IN 1
>> ANI 2
>> JZ TIN
>> IN 0
>> RET
> -- snip --
>
> One thing I found invaluable on my 8080 was the console LED port at
> 0FFh. I'd stick an OUT 0FFH after IN 1 to see what's going on in real
> time. Do you have anything like that on your system? Or at least some
> way to watch port 1? It's clear that the system isn't seeing bit 2 of
> port 1 activate the second time around.
>
> If you can, try and swap it with another 8251, just in case. Like you
> say, I doubt it would be the 8251 because it works once, but it's a
> simple thing to do and it gets it out of the way, just in case it
> happens to be the problem.
>
> What system is this by the way?
>

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