OAM table - handles all sprite tiles. There are 0x80 (128) slots for tiles. Generally, the table is indexed from either $0200 or $0300, with $0300 being used for normal sprites (and Mario) and $0200 being used for various other sprite types.
Note that tiles are drawn to the screen from top to bottom of the table; that is, a sprite in slot 0 will always appear visually on top of a sprite in slot 1.
The actual OAM table consists of two sub-tables:
- $7E0200-$7E03FF (512 bytes): Each slot consists of four bytes in the order of: X position, Y position, tile number, YXPPCCCT. Unused tiles are generally marked by giving them a Y position of #$F0 (which is offscreen).
- $7E0400-$7E041F (32 bytes): Each slot gets 2 bits, used to handle a 9th bit of the X position (for handling sprite tiles that go past the left edge of the screen) and a "size bit" which (generally) controls whether the tile is 8x8 (0) or 16x16 (1). Since each tile only requires 2 bits, each byte of this table actually handles four separate tiles; see the details table for more information. It is not recommended that you write to this table directly, though, and you should use the table at $0420-$049F instead (routine at $008494 takes $0420 data, reformats or compacts it, and stores it to $0400).