INES Mapper 144: Difference between revisions
From NESdev Wiki
Jump to navigationJump to search
(RE'd, stared at incoherently, groaned) |
(No difference)
|
Revision as of 19:36, 2 August 2012
iNES Mapper 144, allocated for the game Death Race, describes a intentionally defective variant of the Color Dreams board (11).
This game's PCB (labelled 50282) is almost identical to the revision B Color Dreams boards, but with the addition of a 300Ω resistor between CPU D0 and both the mapper hardware and the ROM. In this way, the ROM always wins bus conflicts but just for the LSB.
Nestopia-1.4.0 implements this as RealData = (WrittenData & ROM[address]) | (ROM[address] & 1)
FCEUX-2.1.5 works around this by ignoring writes to 0x8000
The most succinct description is RealData = (ROM[address] & (WrittenData|1))
