emulator: EightyOne
type: standalone + libretro
source: "https://github.com/libretro/81-libretro"
upstream: "https://github.com/charlierobson/EightyOne"
profiled_date: "2026-03-18"
core_version: "1.0a"
display_name: "Sinclair - ZX 81 (EightyOne)"
cores:
  - 81
systems:
  - sinclair-zx81

notes: |
  Libretro core embeds zx81.rom and dkchr.rom as C arrays (xxd -i at build).
  Core never calls RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY.
  Standalone EightyOne loads ROMs from filesystem (cwd/ROM/<filename>).

  Original emulator supports ~15 machines (ZX80, ZX81, Jupiter ACE, TS1500,
  Lambda, R470, TK85, ZX97LE, Spectrum variants). Libretro port hardcodes
  MACHINEZX81 — only zx81.rom and dkchr.rom are embedded.

files:
  # mode: standalone = only needed when running as standalone emulator
  # mode: libretro = only needed when running as libretro core
  # mode: both (default if absent) = needed in both modes

  # ref: 81-libretro/81/zx81/snap.c:37,489-496 — embedded as bin_ROM_zx81_rom
  # ref: EightyOne/Source/zx81/snap.cpp:1219-1279 — open(cwd/ROM/zx81.rom)
  - name: zx81.rom
    system: sinclair-zx81
    required: true
    mode: standalone
    size: 8192
    note: "ZX81 8K BASIC ROM. Embedded in libretro core, external for standalone."
    source_ref: "EightyOne/Source/zx81/snap.cpp:1264, 81-libretro/81/zx81/snap.c:489"

  # ref: 81-libretro/81/zx81/snap.c:38,499-508 — embedded as bin_ROM_dkchr_rom
  - name: dkchr.rom
    system: sinclair-zx81
    required: false
    mode: standalone
    size: 4096
    note: "dK'tronics character ROM. Embedded in libretro core."
    source_ref: "81-libretro/81/zx81/snap.c:499"