Both lines are pulsing on my working boardset.
On 11/20/2011 1:42 AM, David Shoemaker wrote:
>
> Anyone have a working Mario Bros board set and a logic probe?
>
> Can you check a couple of signals between the Z80 and the Z80-DMA chip
> for me?
>
> CPU -> DMA chip
>
> 23 !Bus Ak -> 14 !BAI
>
> 25 !Bus Req -> 15 !Bus Req
>
> And then tell me if it is pulsing?
>
> On the board set I am working on both this signals are always high. I
> suspect the DMA is not working correctly but am not sure.
>
> Background:
>
> The boards seem to be running fine, but NO sprites. No logo on the
> title screen, no character sprites on the intro screen and no shells,
> characters, enemies or coins on the play screen.
>
> But the pipes / walkways and text all show up correctly.
>
> I have traced it back to the !OBJRD !OBJWR !OBJRQ signals always being
> high while the game is running.
>
> If using my Fluke 9010 I do a read or write to 0x7000 (start of object
> ram) these signals will go activate low as expected. And the read /
> writes work correctly. So the address decode logic is all working
> correctly.
>
> Oh Barry, no joy on the -5vdc. That is at the ram as needed.
>
> Thanks,
>
> David
>
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Received on Sun Nov 20 08:39:06 2011
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