I, Robot board help needed

Hi all,

        I'm working on one of two I, Robot boards I have (one is
mine...other is already for someone :) ). Anyway, I got number 1 up and
running finally (thanks for the PROM image Clay!) but the graphics are
weird. I am getting no RAM errors. but it looks like half the display is
hosed. In test mode, when viewing the grid screen, only half the grid is
displayed...on the left half of the screen, the grid is fine, but on the
right half, only horizontal ines are present. Moreover, there is a stray
horizontal line present near the middle of the screen.

        Other important things to note : 1> In test mode, dots or polygons
are not drawn, yet some manage to be drawn during normal gameplay.
Vectors seem to be somewhat drawn.

        2> All alphanumerics are fine.

        Both CPU boards I posess have been repaired and seem to work.
This particular problem seems to lie in the video PCB. On the video PCB,
the PROM that generates VSYNC was bad and the SYSCLK and VIDCLR signals
were initially stuck low (found many bad ICs and replaced these).

        Finally, in gameplay mode, again, one half the screen seems
sort-of fine (especially on the title screen), the other half is kinda-of
goofy.

        Any ideas? Sorry to post such a long winded message!

Thanks!

Ed

2^12 /= 1024 (vectorlist screw-up)
        

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Received on Mon Nov 20 10:19:53 2000