---------------------------------------------------------------------------- Galaga memory map, partial, probably wrong in places, but it is a start. Galaga memory map ----------------- V1.0 Nov1/96 'board squirrel' Galaga is a multi processor architecture machine. The processor board is a subset of the Bosconian processor board. In fact a bosconian CPU will run the Galaga code. A galaga video board is required though. Processor 1 ----------- Z80A , clocked at 1H. Board position 4M. Uses 4, 2732 eproms these are mapped at 0000-3FFF sequentially 3N(gg-a),3M(gg-b), 3L(gg-c),3K(gg-d). It uses a sync bus controller (08xx) at 2J to access common system areas. It uses IRQ1, and NMI1. The source of NMI1 appears to be the unknown device at 2L(06xx) Processor 2 ----------- Z80 , clocked at 1H, board position 4J. Uses 1 2732 eprom 3J(gg-e) mapped at 0000-0FFF. It uses a sync bus controller (08XX) at 2J to access common system areas. It uses IRQ2, and NMI2. The source of NMI2 is the 50 way edge connector to the video board, but the video board does not appear to use it. Stack area 9100, accesses video bus D, and the A ram at least. Processor 3 ----------- Z80 , clocked at 1H, the horizontal dot clock frequency Board position 4E. Uses a single eprom (2732) at position 3E(gg-g). This is mapped at 0000-0FFF. It uses a Z80 sync bus conrtoller chip(08xx) at 2E to access common sytem areas. It uses NMI3 and IRQ3. The source of NMI3 is the clock generator IC(07xx) at 4D, but it is enabled by the !NMION signal. It seems to access video ram in the video bus 'D'area. Stack area is 9B00 COMMON SYSTEM AREA ------------------ IC 2P,1P do most of the decoding on the cpu board. 2P AA AAA C11 111 K54 321 001 101 -> !I/O i.e 6800-6FFF 001 110 -> enable 1P 1P EE+ RAA NN5 W54 001 000 -> A6 PROM 5C, sound related 6800+ 001 001 -> WE ram 2B(7489) , sound related. 001 010 -> select register 3C, system control bottom 3 address bits select which bit. 001 011 -> !WDR watchdog reset, must be held each vblank. 001 100 -> read dip switches. A 2 bit read, of 16 switches selected by bottom 3 address bits. ADDRESS SUMMARY --------------- AAAA AA 1111 11AA AAAA AAAA R 5432 1098 7654 3210 W +----+----+----+----+ 0111 0xxx xxxx xxxx X I/O -> IC 2L coin,control,background sound 0110 1xxx xx00 xxxx W A6 prom5C 0110 1xxx xx01 xxxx W 2B 7489 write 0110 1xxx xx10 x000 W d0 clr IRQ1 0110 1xxx xx10 x001 W d0 clr IRQ2 0110 1xxx xx10 x010 W !NMION 0110 1xxx xx10 x011 W !RESET 0110 1xxx xx10 x100 W MOD0 use unknowm 0110 1xxx xx10 x101 W MOD1 use unknown 0110 1xxx xx10 x111 W MOD2 use unknown 0110 1xxx xx11 xxxx W !WDR watchdog reset. 0110 1xxx xx00 x000 R Dip sw read (d0=6k sw0,d1=6j sw0) 0110 1xxx xx00 x001 R Dip sw read (d0=6k sw1,d1=6j sw1) 0110 1xxx xx00 x010 R Dip sw read (d0=6k sw2,d1=6j sw2) 0110 1xxx xx00 x011 R Dip sw read (d0=6k sw3,d1=6j sw3) 0110 1xxx xx00 x100 R Dip sw read (d0=6k sw4,d1=6j sw4) 0110 1xxx xx00 x101 R Dip sw read (d0=6k sw5,d1=6j sw5) 0110 1xxx xx00 x110 R Dip sw read (d0=6k sw6,d1=6j sw6) 0110 1xxx xx00 x111 R Dip sw read (d0=6k sw7,d1=6j sw7) NOTE the IO circuitry contains 2 custom chips, one of which is suspected to be a custom z80 processor. No investigation at this point. VIDEO BOARD ----------- IC 1E does most of the CPU related adress decoding on the video board. CAA AAA K11 111 45 321 010 000 -> !RAM, IC 2K, RAM IC 1K, TMM2016 , 2K*8 bus "A" 010 001 -> IC2F, RAM 3F,3E, Data bus "D" 010 010 -> IC2J, RAM 3L,3K, Data bus "B" 010 011 -> IC2H, RAM 3J,3H, Data bus "C" 010 100 -> !port-> ic 5K IC 04xx decodes some other addresses maybe ? DECODE SUMMARY -------------- AAAA AA 1111 11AA AAAA AAAA 5432 1098 7654 3210 1000 0xxx xxxx xxxx 8000-87FF "A" RAM 1000 1-xx xxxx xxxx 8800-8BFF "D" RAM 8C00 8FFF "D" RAM mirror 1001 0-xx xxxx xxxx 9000 93FF "B" RAM 9400 97FF "B" RAM mirror 1001 1-xx xxxx xxxx 9800 9BFF "C" RAM 9C00 9FFF "C" RAM mirror 1010 0xxx xxxx x000 A000 D0 sets IC5 bit0 1010 0xxx xxxx x001 A001 D0 sets IC5 bit1 1010 0xxx xxxx x010 A002 D0 sets IC5 bit2 1010 0xxx xxxx x011 A003 D0 sets IC5 bit3 1010 0xxx xxxx x100 A004 D0 sets IC5 bit4 1010 0xxx xxxx x101 A005 D0 sets IC5 bit5 1010 0xxx xxxx x110 A006 D0 sets IC5 bit6 1010 0xxx xxxx x111 A007 D0 sets FLIP VIDEO ROM DECODING ------------------ ROM4L (gg-J) is USED by RAM "A" Suspect this is the character ROM