ZXFLASH compiles ZX Spectrum BASIC straight to Flash SWF bytecode running in Ruffle

danbri · x · 2026-10-24

danbri released ZXFLASH: type a ZX Spectrum BASIC program in the browser and JavaScript compiles it directly to an uncompressed .swf, which the open-source Flash player Ruffle executes. Nothing is interpreted in the browser — the BASIC really runs inside the Flash movie.
Implementation: the Spectrum ROM font becomes sprite glyphs, a bank of square-wave DefineSounds provides BEEP, and the program is compiled to AVM1 (ActionScript 1) bytecode with a small runtime; every edit rebuilds and reloads the movie.
Supports line numbers, multi-statement lines, PRINT/AT/TAB/INK/PAPER, INPUT, IF/THEN/ELSE, FOR/NEXT, GO TO/GO SUB, plus extensions like REPEAT/UNTIL, arbitrary #RRGGBB colors, RECT, and Emoji-sprite support.
The author's motivation: this is basically Flash live-coding, but the best game demo in the original was ZX81's 3D Monster Maze, so he built a version with cheery sprites and silly music.

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