v2026.04.02/emulators/b2.yml

emulator: b2
type: standalone + libretro
source: "https://github.com/zoltanvb/b2-libretro"
upstream: "https://github.com/tom-seddon/b2"
profiled_date: "2026-03-18"
core_version: "v0.1"
display_name: "Acorn - BBC Micro (b2)"
cores: [b2]
systems:
  - bbc-micro-b
  - bbc-micro-bplus
  - bbc-master-128
  - bbc-master-compact

notes: |
  b2 is a BBC Micro emulator by Tom Seddon. Libretro port by Zoltan Balogh.
  ref: zoltanvb/b2-libretro, tom-seddon/b2

  Standalone: loads ROMs from etc/roms/ via GetAssetPath().
  ref: tom-seddon/b2/src/b2/roms.cpp:9-10

  Libretro port (experimental): GetAssetPath stubbed in
  src/libretro/adapters.cpp to return relative paths. LoadFile also
  stubbed (returns false). ROM loading mechanism unclear — the 256 ROM
  files are in the repo but the stub suggests they may not load at runtime.
  is_experimental=true in .info.
  ref: zoltanvb/b2-libretro/src/libretro/adapters.cpp

  256 ROM files in etc/roms/ cover: BBC Model B (OS 1.20, BASIC II),
  Model B+ (B+MOS), Master 128 (MOS 3.20, 3.50), Master Compact
  (MOS 5.00, 5.10, I5.10C/Olivetti), parasite processors (65C102 TUBE,
  6502 TUBE), disc interfaces (Acorn 1770, Watford, Opus).

  All ROMs ship with both standalone and libretro repos.
  No external BIOS files needed by the user for either mode.

files: []
# 256 ROMs bundled in repo etc/roms/ — not loaded from system dir
# standalone loads via GetAssetPath("roms", path) -> etc/roms/
# libretro port has LoadFile stubbed — ROM loading mechanism TBD
# is_experimental=true, core may not fully function

# closed-source analysis note: core binary on buildbot contains
# "Retro ROM DIRECTORY" and "system_dir" strings but LoadFile stub
# returns false. needs further investigation when port matures.