Tetris (NES, Nintendo)/RAM map

The following article is a RAM map for Tetris (NES, Nintendo).

0017-0018	16-bit random seed
0019	PieceID of last nextpiece generated by rng
001A	number of pieces this poweron
0033	spun on in wait4vbl loop at AA37
0040	cur piece x
0041	cur piece y
0042	cur PieceID
0044	current speed level
0045	fall timer
0046	left/right autorepeat timer
0047	starting speed level
0048	Current game phase: 1 - active time 2 - start of spawn delay; update bg tilemap 3 - line clear check 4 - wait for line clear animation 5 - update score counter, etc. 6 - A-Type: dummy frame; B-Type: goal check 7 - normally a dummy frame -- contains logic for unfinished 2 player mode 8 - end of spawn delay; prepare next piece
0049	counter for bg tilemap update (used when 0048 == 2)
004A-004D	line numbers being cleared
004E	down autorepeat timer
004F	down hold timer (cleared to 0 on release)
0050-0051	number of lines (BCD little endian)
0053-0055	score (little endian bcd)
0052	line clear animation counter (incremented when frame counter 00B1 % 4 == 0)
0056	number of lines being cleared
0057	line clear check counter (used when 0048 == 3)
0058	game over animation (negative: delay; $00: top; $14: finish)
0059	B-type height level
0060-007F	mirror of 40-5F. If 00BE is forced to equal 2, this block is used for the unfinished 2 player mode.
00A8	copyright notice autoadvance time left
00AC	same as 0042/0062 for collision?
00AD	Playfield base address of current piece for collision?
00AE	Y position of current piece in spritespace
00B1-00B2	demo time: 00B2 set to 0 when title screen appears; goes to demo at 00B5 = 5
00B5	Bits set for 1 frame when NES Controller buttons are initially pressed (ABsSUDLR)
00B6	NES Controller button states (ABsSUDLR)
00B8	Address of the playfield ($0400 for player 1, $0500 for player 2)
00BE	Number of players. Always 1 by default, but forcing it to 2 enables unfinished 2 player Versus functionality.
00BF	PieceID of next piece (valid orientations: $02, $07, $08, $0A, $0B, $0E and $12)
00C1	game type (marathon = 0, 25lines = 1)
00C2	music type (sugarplum = 0, off = 3)
00C3	copyright notice unskippable time left
00F5	controller 1 newly pressed buttons
00F7	controller 1 state (0x80 = A pressed, 0x40 = B pressed...)
00FC	vertical scroll (conjecture based on code at $80C5)
00FD	horizontal scroll (conjecture based on code at $80C5)
00FE	PPUMASK value
00FF	PPUCTRL value
0200	Copy of OAM
03F0-03F1	number of T tetrominoes dealt (little endian BCD)
03F2-03F3	number of J tetrominoes dealt
03F4-03F5	number of Z tetrominoes dealt
03F6-03F7	number of O tetrominoes dealt
03F8-03F9	number of S tetrominoes dealt
03FA-03FB	number of L tetrominoes dealt
03FC-03FD	number of I tetrominoes dealt
0400-0409	Row $00 (top of playfield)
040A-0413	Row $01
04BE-04C7	Row $13 (bottom)
0680-06CF	Music related
06D0-06FF	Sound effects related
0700-075x	high score tables
0718-071D	B-type top name
071E-0723	B-type second name
0724-0729	B-type third name

PieceID

A PieceID is a number representing both a tetromino and an orientation. For instance, $11 is a I up and down, and $12 is an I across. Tetrominoes S, Z, and I have two PieceIDs; O has only one. The others have four. Because the PieceID table is "optimized" in this way, it'll take more extensive asm hacking to get Bombliss or Tetris DS rotation in.

The next piece is stored at $00BF. Poking a value into $00BF that's a valid PieceID but is not the starting orientation for that tetromino results in the next piece being drawn as a solid (not textured) O tetromino, but the next piece is dealt in the proper starting orientation.

Copy of OAM

At $0200 is a copy of OAM, the display list. Usually the falling piece occupies $0200-$020F, and the next piece occupies $0210-$021F.