Thursday, November 3, 2011

JAMMA Space Invaders experiment.

33 years ago a game caught the eyes (and ears) of many people in Japan, and later everywhere else. You can read the whole story here of course, but this is not the subject of this post.

This post is about a little experiment I made in fixing and converting an original Midway Space Invaders motherboard to run in with JAMMA harness or standalone machine.

A Few notes:

-The coin input, and controls are all mapped.

-The video is now RGBS (same signal send to R, G and B, and sync tapped from somewhere else.

-The only thing that doesn't follow the JAMMA spec is the audio output, since my mod requires a separate amp (like many other games like all Nintendo stuff and Mr.DO), so its obvious that any collector has those already. The SI daughterboard requires raw 18V+center tap directly from the transformer which I don't have (using a standard PC psu here)

-Game now uses one 27128 EPROM and not 4 to 8 separate 2716 (9316B or whatever)

-No color overlays .. duh!


  1. I wish this blog had more posts, the research you do is really interesting!

    Also, I wish chipsounds had opl2-opl3 emu's. I understand leaving out FM chips per se, but these chips are unusual sounding and different enough to warrant standing out in the crowd, as well as there importance in video game history, which is tied to chipsounds somewhat FWIW. Or maybe a generic 2-op engine and generic 4-op engine that covers them all somewhat (opl, opn, opm etc)

    Just wanted to throw that out there to share my thoughts. BTW, Chipsounds is amazing and I cant wait for the new effect plug!


  2. Hi Matt.
    I've already got an OPL core going on, but it ont be in before 2.0. I'm currently working on a few things including chipsounds 1.6 update. so blog posts sadly take the side...

    1. Hello David, can You more specify the 27128 HACK ?
      I would like to the same with my board.

      Thank You


    2. For the rom:
      In DOS/command line:

      copy /b m739h.bin+m739g.bin+m739f.bin+m739e.bin 27128.bin

      Thing is, there are lots of revisions of the main 8080 board, i connected my pins using the schematics here:

      It was pretty obvious to connect the extra 27128 address lines

  3. Erm rom names might have changed in MESS:

    ROM_START( invaders )
    ROM_REGION( 0x10000, "maincpu", 0 )
    ROM_LOAD( "invaders.h", 0x0000, 0x0800, CRC(734f5ad8) SHA1(ff6200af4c9110d8181249cbcef1a8a40fa40b7f) )
    ROM_LOAD( "invaders.g", 0x0800, 0x0800, CRC(6bfaca4a) SHA1(16f48649b531bdef8c2d1446c429b5f414524350) )
    ROM_LOAD( "invaders.f", 0x1000, 0x0800, CRC(0ccead96) SHA1(537aef03468f63c5b9e11dd61e253f7ae17d9743) )
    ROM_LOAD( "invaders.e", 0x1800, 0x0800, CRC(14e538b0) SHA1(1d6ca0c99f9df71e2990b610deb9d7da0125e2d8) )

  4. Just took a picture of my board, if you are lucky enough and its the same, then there you go... Otherwise, i REALLY need to redo mine, yuck