Vanguard to Nibbler?

The red jumper on the back of the CPU board near the edge connector is for the address space. To get this board going, I'd start by burning the missing roms for Nibbler and fixing that jumper on IC6 that has come loose. All the rest of the work looks to have been done for you. If your going to make a Jamma adapter, note that pin 1 on the CPU board is on the right if you are facing the edge connecter. In the Jamma convention, pin 1 is on the left. Don't get that backwards, the 12v and 5v are in mirror positions on the edge.

Nibbler does have a sound rom (IC53) where Vanguard has a SN76477. That sound rom just supplies the coin-up sound effects (7 sounds which rotate until 9 credits, then uses the same sound for additional credits). On Vanguard the extra SN76477 is used for the two phaser sounds (shot A, shot B on the schematics).

IC51 on most Nibbler boards is empty. However if you put a sound rom from Pioneer Balloon or Fantasy (and probably Vanguard) in that socket, you'll hear music in Nibbler for the first 14 waves. Some Nibbler boards in the wild have IC51 from Pioneer Balloon. In MAME, the Nibbler6p rom set includes IC51 from Pioneer Balloon, if you want to try it out.

PS - This thread on my FPGA project for Nibbler/Fantasy/Pioneer Balloon (and Vanguard) talks a lot more about the hardware variations between these games that all the share the same platform: https://forums.arcade-museum.com/showthread.php?t=373372
 
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Traced the jumpers in the schematic and it looks like, yep, they lead to the CSYNC output pin on the card edge. Taking care of the rest of the empty sockets shouldn't be too huge a problem - won't be able to address them for a few weeks, though. As for the hack on the back of the top board, I traced around and went through the schematic and it looks like it heads off into the sound system (see below). Not sure which direction to head in with adjusting the address space. :(



IC73 looks like someone tried to pull it while it was still soldered in place - it'll get replaced as well. As for the rest of the jumpers, I know Mark said he thought they might be for the address space swap, but it looks like they do actually flow into the sound system. This Vanguard PCB has two 76477s, one of which is where a Nibbler sound ROM looks like it should go (IC53) on some Nibbler boards. There are two ROMs (IC51 and IC52) labelled NA and NB on this PCB where some Nibbler boards have one and some have two ROMs (the Olympia boardset looks like it only uses one). Any thoughts?

Aside from sound, and because I'm still trying to understand TTL logic on a large scale like this, where would be the place to start looking on this PCB for swapping the address space? Once I start trying to seriously abstract myself from basic logic, I start getting lost. :( Any input or advice would be tremendously appreciated; thanks to you both for the guidance!
Hi, I purchased a Nibbler card that is exactly identical to yours. Mine was also Vanguard in the beginning but it probably wasn't definitively converted because I don't have all the connections you have on the lower PCB (sk5). I wanted to know if you were able to make it work and if possible have a detail of the changes to replicate on the my. Thank you very much.
 
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