ZX80 file formats

The ZX80's native binary is the .O file, which doubles as the in-memory image the IDE's emulator injects and as the import format that round-trips back to editable source. The machine also exports and imports a cassette .wav (see Cassette audio below). ZX80 has no named files.

For the shared editor .txt, .zip project bundle, escape notation and the cross-machine machine-code overview, see the file formats overview. See also the ZX80 BASIC reference and its escape codes.

ZX80 .O

A straight RAM dump from 0x4000 (the start of the 40-byte system-variable block) up to the byte before E_LINE - exactly what the ROM's SAVE writes and LOAD reads back. Layout: system variables | tokenized program | 0x80 variables-end marker. The edit line and display file are not part of the image; the ROM rebuilds them on load. The system-variable values were captured from the real ROM on an empty machine and have their pointers recomputed for the program length.

Hidden machine-code lines (line number 0, duplicate numbers, large non-printable REM bodies) import as #BIN <base64> directives exactly as for the ZX81 .P format; the only difference is the record shape - ZX80 records are u16 BE line number + body + 0x76 with no length field, so a body can never embed a stray 0x76.

Cassette audio

The ZX80 exposes a .wav export (and "play through speakers") and a cassette-audio import - listening on the mic / line-in, or decoding a .wav recording, back into editable source. The encoder emits mono 44.1 kHz and offers a "robust" mode that lengthens the leader for temperamental hardware.

The tape scheme is the one described under Delivering the image in the serial bridge protocol: bytes MSB-first, 0 = 4 pulses, 1 = 9 pulses, ~1300µs inter-bit gap, 2s leader (4s robust). The ZX80 has no named files and writes the raw .O image. The decoder estimates its bit timing from the recovered signal rather than assuming absolute durations, so decoding is immune to playback / clock-speed drift, resampling and sample-rate mismatch.