SGDK Cartridge

Keep common code and assets reachable while loading different parts of a large ROM. Use the mapper the target cartridge actually supports. Banking is a board feature, not extra RAM or a way around VRAM and DMA limits.

Establish the target

1. Identify ROM size, intended emulator/flash cart/physical board, SRAM wiring, and existing linker layout. Ordinary cartridges expose up to 4 MiB linearly; using SRAM can overlay part of that window. Do not add banking to a small game without a reason.
2. Pull ewrogers/sgdk:latest, run doctor, and inspect its inc/mapper.h, inc/config.h, md.ld, ResComp manual, and the chosen audio driver's source. The references below were checked with SGDK 2.11. Review differences when the image changes.
3. Separate physical ROM offsets from CPU addresses. Write down who owns each mapper window, which resources must stay pinned, and when a temporary view may change. See mapping and resource lifetime.