Source · Code · rom

Tetris (USA)

1989. “Tetris (USA).”

Cite as
“Tetris (USA)”
Licence
proprietary; never redistributed (docs/data-policy.md#roms)
Credit
Nintendo
Notes
No-Intro name and NES 2.0 header: 32 KB PRG ROM, 16 KB CHR ROM, mapper 1 (MMC1), no battery. Without the 16-byte header the SHA-1 is fd9079cb5e8479eb06d93c2ae5175bfce871746a. With the iNES header that CelestialAmber/TetrisNESDisasm's tetris.asm writes instead, the file's SHA-1 is the disassembly's tetris.sha1, so that disassembly is this game (probes/tetris/tetris-nes.mjs checks it). Measured in headless Mesen by probes/tetris/tetris-nes.lua.

Cited on

Claims (5)

The disassembly builds the No-Intro Tetris (USA) ROM exactly; with the iNES header tetris.asm writes in place of the ROM's NES 2.0 header, the file's SHA-1 is the one in tetris.sha1.0x0-0xFVerified
Gravity comes from framesPerDropTable; a piece falls one row every 48 frames at level 0, never more slowly at a higher level, holding steady across levels 10–12, 13–15, and 16–18, down to 2 frames at levels 19–28, and 1 frame from level 29 on.0x99E-0x9BBVerified
Holding Left or Right moves the piece at once, again 16 frames later, and then every 6 frames; the press zeroes autorepeatX, each held frame adds 1, and at DAS_RESET (16) the piece moves and the count drops to DAS_DELAY (10).0x9BE-0xA19Verified
The random number generator is a 16-bit linear feedback shift register at $0017; each step shifts it right and feeds bit 1 XOR bit 9 into the top bit, and from its seed, $8988, it repeats after 32,767 steps.0x2B57-0x2B6DVerified
In 4,800 pieces dealt by the running game, 4.46% repeated the piece before, against 4.03% simulated and 14.3% for a uniform pick; 6.29% of O and S pieces repeated (simulated 6.25%) and 3.76% of the others (3.13%).0x1917-0x194A0x2B57-0x2B6DVerified