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TQROM is an MMC3 variant that supports both CHR ROM and CHR RAM simultaneously. Bit 6 of CHR bank register values selects between CHR ROM and CHR RAM, allowing up to 64KB CHR ROM and 8KB CHR RAM on the same cartridge. This is used by Pin-Bot and High Speed, both developed by Rare. The implementation adds a canWriteChr() method to the mapper interface that the PPU uses to determine if a pattern table address can be written to, replacing the hardcoded vromCount check. Mapper119 stores CHR RAM separately and routes bank switches appropriately based on bit 6. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Implements mapper 119 (TQROM), an MMC3 variant that supports both CHR ROM and CHR RAM simultaneously. Bit 6 of CHR bank register values selects between CHR ROM (0) and CHR RAM (1), enabling mixed cartridge configurations used by Pin-Bot and High Speed (Rare).
The implementation adds a
canWriteChr()mapper interface method that the PPU uses to determine if pattern table addresses can be written to, replacing the previous hardcoded check. Mapper119 maintains separate CHR RAM storage and routes bank switches appropriately.Test plan
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