Space Invaders - relationship between Mother/Daughter boards?

hindered

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Space Invaders - relationship between Mother/Daughter boards?

So, I have two SI motherboards, and three SI daughter boards. I have one of the motherboards working. When using daughter board A, I get perfect gameplay, but no sounds. When using daughter board B (which is actually an Invader's Revenge sound board), the game boots far enough to show player 1 / high /player 2 scores but nothing else happens. When using daughter board C, the game boots to garbage.

If the motherboard is the same and works, what's different about these daughter boards that the game won't play with two of them? I was under the assumption that the daughter board was 100% for sound only, and also for collecting the player inputs / coinup.

EDIT: When I try to boot w/ the Invader's Revenge sound board & Invaders Revenge Roms, the game boots to garbage. :\

DOUBLE EDIT: for clarity.
 
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The daughterboards are more or less what makes the games besides the roms. The programming mostly talks to the daughterboard more than anything - its more than a sound board although thats what a majority of it does.
 
The daughterboards are more or less what makes the games besides the roms. The programming mostly talks to the daughterboard more than anything - its more than a sound board although thats what a majority of it does.

The daughterboard doesn't do much other than sound, I/O and bit shifting for the graphics....

If it's loading down the CPU bus due to shorts, it'll keep the game from booting though... reset/watchdog circuitry is also there for the boards that use it, so that can keep the game from booting.

If you try to use an original SI sound board with deluxe (and perhaps a couple other boots), it'll reset in a loop, since the ROMs check to see that you've got a deluxe sound board instead of an SI....
 
Ok, so the short version is: 99% of what the board does is sounds & IO, but if somethings wrong it can indeed stop the game from booting.

RE the SI/SID mismatch, I'll try to post pics of my mother/sound boards tonight so we can hopefully identify whether or not I've got a mismatch there, which would explain why the 2nd motherboard doesn't seem to work, but passes ram test & is strapped properly.
 
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