iNES Mapper 177 is used for games from 恒格电子 (Hénggé Diànzǐ). It's basically oversize BNROM without bus conflicts, with an additional mirroring control, and with 8 KiB of battery-backed WRAM at CPU $6000-$7FFF.
7 bit 0 --------- $8000-FFFF: ..MP PPPP |+-++++- Select 32 KiB PRG-ROM bank at CPU $8000-$FFFF +------- Select nametable mirroring 0: Vertical 1: Horizontal
Some Hengedianzi games use hard-wired mirroring and do not set the M bit correctly; they are set to INES Mapper 241 instead.
Categories: Mappers with CHR RAM