PPU Registers

Introduction

PPU (also knowing as Picture Processing Unit) is a co-processor of SNES used to send video data to TV. It includes a lot of registers that can be used to do graphic effects.

Registers $2100~$21FF

$2100: Screen Display

Format:

x---bbbb

x = Force blank on when set. bbbb = Screen brightness, F=max, 0="off".

Note that force blank CAN be disabled mid-scanline. However, this can result in glitched graphics on that scanline, as the internal rendering buffers will not have been updated during force blank. Current theory is that BGs will be glitched for a few tiles (depending on how far in advance the PPU operates), and OBJ will be glitched for the entire scanline. Also, writing this register on the first line of V-Blank (225 or 240, depending on overscan) when force blank is currently active causes the OAM Address Reset to occur.