zohassadar/TengenTetrisDisasm

Cite as: zohassadar/TengenTetrisDisasm
Original: https://github.com/zohassadar/TengenTetrisDisasm
Pinned: zohassadar/TengenTetrisDisasm @ df38b4ff812bc57c1fa356665aa3b1439620b337
Accessed: 2026-10-21
Licence: LICENSE holds an MIT-style warranty disclaimer for the disassembly's own files; the game is Atari Games/Tengen's
Credit: Disassembly by zohassadar. Its README credits ejona86's taus project for the info-file structure and tetris-ram.awk, qalle2's nes-util for the CHR tools, and kirjavascript's TetrisGYM.
Notes: Builds with cc65 to a ROM whose SHA-1 is in tetris.sha (34113a10…); the atlas has no copy of the Tengen ROM, so the build hasn't been compared with a No-Intro dump here. main.asm is generated from main.infofile and is only partly labeled; some zero-page names (ppuControl, ppuMask) are reused as the generator's bytes when indexed by X. Line numbers refer to main.asm at the pinned commit.

Cited on

`getNextTetromino` steps the player's 16-bit generator five times and keeps the low three bits, trying again only when they are 0; the result, 1 to 7, is the next piece, with no check against the piece before.	`main.asm L3693–3705main.asm L3805–3832`	Code
At the start of a game both players' generators are loaded with the same seed, and only `getNextTetromino` steps them, so in a two-player game both players get the same sequence of pieces. The shared seed itself is stepped on every pass of the main loop before the game.	`main.asm L3319–3326main.asm L48–50`	Code