Need a hand trouble shooting a Mario Bros

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 01:43:10 2011