This program tests the hardwired mirroring of discrete logic mappers (no, AxROM switchable mirroring is not fully implemented; it's treated as hardwired single-screen) and the switchable mirroring of MMC1. It also reports whether it finds CHR ROM or CHR RAM. It works on Nestopia and Nintendulator; who wants to be the first to report how it works on an NES?
Source and binary (temporary private URL until it's tested on an NES):
http://pics.pineight.com/nes/mmc1test.7z
Result in emulators:
Nintendulator and Nestopia wrote:
MIRRORING:
MODE 0:AAAA (one-screen mirroring corresponding to $2000)
MODE 1:BBBB (one-screen mirroring corresponding to $2C00)
MODE 2:ABAB ($2000 matches $2800; vertical mirroring)
MODE 3:AABB ($2000 matches $2400; horizontal mirroring)