Re: sega I/O

On Wed, 8 Oct 1997 13:02:08 -0800, Clay Cowgill <clay@supra.com> wrote:

>>Did I send you the sources to my simulator, Clay?
>>It's really simple to add code to it to print out every
>>occurance of an I/O access into the debug window.
>>That was the way that I figured out what I/O locations
>>were hit to verify the information in my programming
>>reference.
>
>Uhhh, no. I don't think you did. That'd be handy for some other stuff
>actually. Can I build it with CodeWarrior 9 or 10? (I think that's the
>latest Mac stuff I have...)
>
>As is, I just used a disassembly and searched the whole thing for
>occurrances of stuff like DB F8 (the DB could be wrong, I don't recall--
>it's just the hex equivalent of "IN A,"). I can always just go look for
>the opcode for IN A,(C)...

I looked it up quickly in a Z-280 reference book (a superset of the Z-80,
so there's a chance this is wrong, but I believe it to be correct from my
old Z-80 days), it looks like your going to have to check for:

   IN A,(C)
   IN B,(C)
   IN C,(C)
   IN D,(C)
   IN E,(C)
   IN H,(C)
   IN L,(C)
   IN (addr),(C)
   IN (HL+dd),(C)
   IN (IX+dd),(C)
   IN (IY+dd),(C)

And if there doing trick code:

   IN (IXH),(C) ; load into the high byte of the IX register
   IN (IXL),(C) ; load into the low byte of the IX register
   IN (IYH),(C) ; " IY "
   IN (IYL),(C) ; " IY "

The last four instructions were undocumented in the Z-80 programmers
reference (but supported by the Z-80), but ARE documented in the Z-280
programmers reference. I doubt if you'll have to worry about these, but
then again if you get to the point where there is just nothing left to
try...

-Zonn

   
>
>Source would be handy though if you want to throw it my way. In particular
>I'd like to see if there are any RAM locations that aren't used (and
>common) between the games... :-)
>
>-Clay
>
>Clayton N. Cowgill Engineering Manager
>_______________________________________________________________________
>/\ Diamond Multimedia Systems, Inc. clay@supra.com
>\/ Communications Division http://www.supra.com/
>
>
Received on Wed Oct 8 13:20:28 1997