sega-master-system-devkitsms

name

sega-master-system-devkitsms

description

Program, build, debug, and port Sega Master System (and Game Gear / SG-1000) homebrew games in C with devkitSMS (SMSlib + PSGlib) and the SDCC Z80 compiler. Use whenever the user writes, compiles, fixes, optimizes, or ports an SMS/Master System or Game Gear game or demo: the SDCC + devkitSMS toolchain; producing a `.sms`/`.gg` ROM; VDP tiles, the tilemap, hardware sprites, palettes, PSG music/SFX, joypad input, VBlank/line interrupts, ROM bank switching, SRAM saves; converting assets (`.psgcompr` tiles, `vgm2psg` music, `folder2c`/`assets2banks`); or debugging the classic "compiles but boots to a black screen" failure. Trigger on mentions of devkitSMS, SMSlib, PSGlib, SDCC `-mz80`, ihx2sms, crt0_sms, `SMS_addSprite`/`SMS_waitForVBlank`, a `.sms` ROM, Master System / Game Gear homebrew, or Haroldo-OK's SMS games (Jill of the Jungle, Dangerous Dave, Food Fighter, Sub Rescue, Commander Keen). Prefer it over general knowledge for the SMS toolchain, VDP limits, or ROM format — easily gotten wrong from memory.

Sega Master System game development & porting (devkitSMS)

This skill turns an idea — or an existing game to port — into a playable, verified .sms ROM, built with SDCC (Z80 C compiler) and devkitSMS (sverx's SMSlib + PSGlib). It bundles a consistent toolchain snapshot, project templates, a headless test emulator, and references distilled from Haroldo-OK's open-source SMS games.

The SMS is a Z80 with a tile/sprite VDP (256×192, two 16-colour palettes, ≤64 sprites / 8-per-line), a 4-channel PSG, and 8 KiB of RAM. There is no framebuffer and no float unit. Success means respecting those limits, not fighting them.

Do not rely on memory for SMSlib signatures, VDP addresses, build flags, or the ROM header — they are precise and version-sensitive. Read the references and verify by building and by running the test harness.

Definition of done (do not stop at "it compiled")

A ROM that links tells you almost nothing; the default failure is a clean build that . A task is done only when all hold — report each: