Can I swap Sega System 16B ROM boards?

Crowquill

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In a recent haul of boards a couple friends and I got Golden Axe and ESWAT.
GA runs perfectly, but ESWAT has no sound, so I was going to swap the ROM boards to troubleshoot. But once swapped the games won't start up at all. Both boards still have suicide batteries/processors. I did notice that there are jumpers on the ROM boards that were set differently (pic attached). I'd understood that the ROM boards could be swapped. There's a flyer where ESWAT was even sold as a "junior" kit to convert old 16B games including GA.

Can the ROM boards be interchanged between them? All the main boards seem to be identical (numbers, markings, components).
 

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If I understood it correctly, none of the boards now boot. I guess it is time to get the unencrypted ROMset installed together with a regular 68000. Depending on the type of the ROM board, the install location of the unencrypted ROMs will be different. If you don't have the tools you can get everything from here:

Www.segaresurrection.com
 
They both boot fine WITH suicide batteries. Don't know if the batteries were replaced or these boards are just lucky. They only won't boot when the ROM boards are swapped. Replacing the suicide batteries is definitely on my to-do list. I already have a de-suicided Shinobi, so I'm familiar with the process.

After I started this thread I stumbled onto this where they sorted out that the jumpers set what type/size EPROM is being used.
 
Each System 16B game has its own custom CPU, refers to MAME source:

http://git.redump.net/mame/tree/src/mame/drivers/segas16b.cpp

So if you want to swap a ROM board, you need to swap also the custom CPU for that specific game.So, first identify your ROM sets among these:

GAME( 1989, eswat, 0, system16b_fd1094_5797,eswat, segas16b_state,generic_5797, ROT0, "Sega", "E-Swat - Cyber Police (set 4, World) (FD1094 317-0130)", 0 )
GAME( 1989, eswatu, eswat, system16b_fd1094_5797,eswat, segas16b_state,generic_5797, ROT0, "Sega", "E-Swat - Cyber Police (set 3, US) (FD1094 317-0129)", 0 )
GAME( 1989, eswatj, eswat, system16b_fd1094_5797,eswat, segas16b_state,generic_5797, ROT0, "Sega", "E-Swat - Cyber Police (set 2, Japan) (FD1094 317-0128)", 0 )
GAME( 1989, eswatj1, eswat, system16b_fd1094, eswat, segas16b_state,generic_5704, ROT0, "Sega", "E-Swat - Cyber Police (set 1, Japan) (FD1094 317-0131)", 0 )


GAME( 1989, goldnaxe, 0, system16b_i8751_5797,goldnaxe, segas16b_state,goldnaxe_5797, ROT0, "Sega", "Golden Axe (set 6, US) (8751 317-123A)", 0 )
GAME( 1989, goldnaxeu, goldnaxe, system16b_fd1094_5797,goldnaxe,segas16b_state,generic_5797, ROT0, "Sega", "Golden Axe (set 5, US) (FD1094 317-0122)", 0 )
GAME( 1989, goldnaxej, goldnaxe, system16b_fd1094, goldnaxe, segas16b_state,generic_5704, ROT0, "Sega", "Golden Axe (set 4, Japan) (FD1094 317-0121)", 0 )
GAME( 1989, goldnaxe3, goldnaxe, system16b_fd1094, goldnaxe, segas16b_state,generic_5704, ROT0, "Sega", "Golden Axe (set 3, World) (FD1094 317-0120)", 0)
GAME( 1989, goldnaxe2, goldnaxe, system16b_i8751, goldnaxe, segas16b_state,goldnaxe_5704, ROT0, "Sega", "Golden Axe (set 2, US) (8751 317-0112)", 0 )
GAME( 1989, goldnaxe1, goldnaxe, system16b_fd1094_5797,goldnaxe,segas16b_state,generic_5797, ROT0, "Sega", "Golden Axe (set 1, World) (FD1094 317-0110)", 0 )
 
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Thanks Calus! I was just pulling this up to give an update. It occurred to me last night that if they're encrypted then each game probably has it's own key. The labels on my CPUs are unreadable. I swapped both the ROM board and CPU this morning and I can play ESWAT with all sound and music. Won't have to worry about this restriction once I swap out the processors and burn unencrypted ROMs. I'd guess the ESWAT "Junior" kit was the ROM board and FD1094 CPU.

Unfortunately I also discovered that during this adventure I bent a couple of the pins on the original ESWAT's main board on one of the ROM board connectors. I might be able to bend them back and they may not even be used since the game was working without sound. I'll work on fixing the board's audio issue and see if I still have problems before replacing that. Either way, I've got some fixin' to do.

Also this means I could swap the standard 68000 and ROM board and play the Shinobi I've had for 10+ years for the first time with sound!
 
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