Way of the Exploding Fist

01 · The backdrops

Four pictures in 13 kilobytes

The backdrop changes every stage, and the disk is never read after loading. All four pictures sit in memory packed, and are unpacked into the bitmap when the stage begins.

The bitmap is packed as runs, read from the end of the stream backwards and written from the bottom of the picture up ($F53F down to $E640): a control byte below $80 copies that many bytes, one above repeats a single byte. The colours are packed separately as four-bit values, in three passes over the 480 colour cells. Each picture covers character rows 5 to 16, the band between the score panel and the floor.

The floor below never changes. Its colours are all set to yellow ($192F), so whatever the bitmap holds there is invisible, and the game keeps its speech samples in that hidden part of the bitmap ($F540-$FFDC).

02 · The judge

The seated judge is painted into every picture

Each backdrop has a small seated figure at one side. When a bout is decided, the game puts two sprites over him, at a position kept for each backdrop, to signal the winner.

The end of a two-player game, captured in the emulator. judge_decision ($1F93) takes the sprite pointer and the position from four-entry tables indexed by the backdrop ($1FFA-$2009).