Asteroids Vector rom access

I've been fighting an asteroids board most of the day. V. 4 board Problems
ranging from shorted ram lines, to bad dataline buffers etc. I've almost got
this thing to run, but when I do sigs on the Vector rom, they are unstable.
They are also unstable on R2 the VG data buffer. All other sigs look good.
I thought that the data buffer was bad, as it looks like it uses DMA to
access the vector rom at np3. So I went ahead and swapped it out, but still
getting unstable sigs. I'm using a known good rom. Just seem to be having a
hard time wrapping my tiny brain around how the vg rom is accessed, and what
could be causing the bad sigs.

I've triple checked my setup, and it looks good. The NOP setup sig checks
out..

Can anyone help me get a better understanding of what could be happening
with the Vrom?

Thanks,

Kevin

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Received on Wed Jan 20 11:19:53 2010