Delving into how CPS-2 B boards work

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    • Delving into how CPS-2 B boards work

      I'm studying a bit how CPS2 B board works and so far I've understood what roms hold which and how the jumpers and PALs work.

      Now I'm seeing that there are some "add-on" boards like those holding SIMMs and other ROMs such as the yellow rental carts and I'm intrigued about how they work.
      MAME's sourcecode actually explains quite a lot but doesn't say exactly how each SIMM and ROMs match.

      So, let's say we have Progear which has 4 SIMMs, each holing a certain amount of TSOP roms.

      (for reference: progettoemma.net/gioco.php?game=progear )

      Let's take for example SIMM 1 and 3 which hold the gfx data, splitted into 4 single roms, so we have:

      simm.01a/b/c/d
      simm.03a/b/c/d

      We know GFX roms are located on sockets 13 to 20 on the main B board.

      Now, we want to put the data from those SIMMs onto EPROMs on the main B Board, and here's where I'm stuck: where do we put what?

      Is it just

      simm.01a -> 13
      simm.01b -> 14
      etc... ?

      Or is the data interleaved? I've seen Avalaunch ROMs uses only 4 EPROMs for gfx which means that he has combined two.

      For reference, I'll leave the cps2 MAME driver here with all the relevant information: git.redump.net/mame/tree/src/mame/drivers/cps2.cpp

      Thanks to all those who'll want to contribute!

      EDIT: after some more research, I've found out that Artemio has made a utility to convert CPS2 EPROM data to put it into the SIMMs through a CPS-3 and darksoft's utility, so there definitely exist a correlation between the two. I've also found a user in this forum which has used this method to put Street Fighter Alpha 3 on the SIMMS of his Black CPS2 board, so it's definitely possible to do EPROM -> SIMM, which leads me to think that it must be possible to do the opposite.

      The post was edited 2 times, last by donluca: Additional info ().