[May/14/2001]

VIC Dual Game board

Seems like there are 2 types of boards. One uses an 8080A and 2 control PROMs
and the other is a Z80 with 1 control PROM.


0000-3fff ROM
4000-7fff ROM mirror image (used in most games)

the following have mirror images throughout the address space
e000-e3ff Video RAM + work RAM
e400-e7ff RAM
e800-efff Character generator RAM

I/O ports:

The memory map is the same for many games, but the I/O ports change. The
following ones are for Carnival, and apply to many other games as well.

read:
00        IN0
          bit 0 = connector
          bit 1 = connector
          bit 2 = dsw
          bit 3 = dsw
          bit 4 = connector
          bit 5 = connector
          bit 6 = seems unused
          bit 7 = seems unused

01        IN1
          bit 0 = connector
          bit 1 = connector
          bit 2 = dsw
          bit 3 = vblank
          bit 4 = connector
          bit 5 = connector
          bit 6 = seems unused
          bit 7 = seems unused

02        IN2
          bit 0 = connector
          bit 1 = connector
          bit 2 = dsw
          bit 3 = timer? is this used?
          bit 4 = connector
          bit 5 = connector
          bit 6 = seems unused
          bit 7 = seems unused

03        IN3
          bit 0 = connector
          bit 1 = connector
          bit 2 = dsw
          bit 3 = COIN (must reset the CPU to make the game acknowledge it)
          bit 4 = connector
          bit 5 = connector
          bit 6 = seems unused
          bit 7 = seems unused

write:
	(ports 1 and 2: see definitions in sound driver)

08        ?

40        palette bank


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