iNES Mapper 142 represents a PCB used for several of Kaiser's unlicensed ports of FDS games. Its UNIF board name is UNL-KS7032, and it features the KS202 ASIC, which is an upgrade to Konami's VRC3.
Writes set IRQ reload value, in four four-bit words, same as VRC3
Kaiser's SMB2J writes $02 or $05 to enable, and $00 to disable, indicating that bits 1 and 2 may function similarly to the VRC3.
Any write to this register will acknowledge the pending IRQ, like VRC3. Unlike a VRC3, $C000 bit 0 must not be moved to bit 1, otherwise SMB2J will freeze.
Select one of four bank registers to update on next write to $F000.
7 bit 0 ---- ---- .... .RRR ||| +++- Specify which bank register to update on next write to Bank Data register 1: Select 8 KB PRG bank at CPU $8000-$9FFF 2: Select 8 KB PRG bank at CPU $A000-$BFFF 3: Select 8 KB PRG bank at CPU $C000-$DFFF 4: Select 8 KB PRG bank at CPU $6000-$7FFF 6: Writes to $F000 have no effect 0,5,7: unknown
7 bit 0 ---- ---- .... DDDD |||| ++++- New bank value, based on last value written to Bank select register (mentioned above)
Categories: INES Mappers, FDS conversion mappers, Mappers with CHR RAM, ASIC mappers, Mappers with cycle IRQs