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RetroBIOS

b2

b2 emulates Acorn BBC Micro Model B, Acorn BBC Micro Model B+, Acorn BBC Master 128 and Acorn BBC Master Compact. It reads 44 files, 10 of them required: without a required file it does not start games. A required file is needed only by the machines that use it. Each file below cites the line of source code that reads it.

About this profile
Detail Value
Type standalone + libretro
Classification Community fork
Source https://github.com/zoltanvb/b2-libretro
Upstream https://github.com/tom-seddon/b2
Version v0.4, stated in src/libretro/core.cpp
Revision zoltanvb/b2-libretro@9793f6a8040c, tom-seddon/b2@e1c9b84a9460
Profiled 2026-03-23
Profile YAML, JSON
Cores b2
Systems Acorn BBC Micro Model B, Acorn BBC Micro Model B+, Acorn BBC Master 128, Acorn BBC Master Compact
Technical notes

Libretro port by Zoltan Balogh of Tom Seddon's b2 BBC Micro emulator. is_experimental=true in .info. ref: zoltanvb/b2-libretro, tom-seddon/b2

Standalone loads ROMs through BeebROM::GetAssetPath(), which resolves roms/<path> under the assets folder: assets/ beside the executable on Windows and Linux, ../Resources/assets on macOS. Linux then tries ../share/b2 when the executable sits in bin/, XDG_DATA_HOME/b2 and each XDG_DATA_DIRS entry. The build copies etc/roms into that folder, flattening acorn/, watford/ and opus/ and lowercasing M128/ and MCompact/. ref: src/b2/roms.cpp:9-10 ref: src/b2/load_save.cpp:171-179, src/b2/load_save.cpp:200-284 ref: src/b2/CMakeLists.txt:285-325

Each configuration names one OS ROM, up to 16 sideways ROMs and an optional second processor OS. Default configurations: six Model B disc interfaces, B+, B+128, Master 128 and Master Turbo on MOS 3.20 and 3.50, B with 6502 second processor, Master Compact on MOS 5.00, 5.10 and 5.11i, and the Olivetti PC 128 S on MOS I5.10C. ref: src/b2/BeebConfig.cpp:212-462

Libretro port embeds all ROMs as hex arrays in src/libretro/roms.hpp. create_core() loads OS and sideways ROMs from static machine_types[] arrays. GetAssetPath() and LoadFile() are stubbed: no file I/O at runtime. ref: zoltanvb/b2-libretro/src/libretro/roms.hpp ref: src/libretro/core.cpp:275-305 ref: src/libretro/adapters.cpp:74-78

9 machine types: B/Acorn 1770, B/Watford DDB2, B/Watford DDB3, B/Opus 1770, B/Opus Challenger 256K, B/Opus Challenger 512K, B+, B+128, Master 128 (MOS 3.20). Master 3.50, Master Turbo, Master Compact not yet implemented. ref: src/libretro/core.h:117

Files

Section titled “Files”

24 files (44 accepted versions): 6 required, 18 optional.

In this collection: 6 in repo and 18 missing.

Required

Section titled “Required”
FileStatusHash

OS12.ROM

OS 1.20

  • Standalone path: assets/roms/OS12.ROM
  • System: Acorn BBC Micro Model B
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window. The B/Acorn 1770 configuration is the one b2 falls back to when no saved configuration loads, so a missing file stops startup.
Hashes and source
required for Acorn BBC Micro Model B in repo standalone installed with the standalone emulator MD5 0a59a5ba15fe

B+MOS.rom

B+ MOS

  • Standalone path: assets/roms/B+MOS.rom
  • System: Acorn BBC Micro Model B+
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 1a663b9d1022
Hashes and source
required for Acorn BBC Micro Model B+ missing standalone installed with the standalone emulator MD5 47a1eff6c7fb

MasterTurboParasite.rom

65C102 TUBE 1.20 (Master Turbo)

  • Standalone path: assets/roms/MasterTurboParasite.rom
  • System: Acorn BBC Master 128
  • Second processor OS ROM, read only by configurations with that parasite. A failed load, or an image over 4 KiB, aborts loading the configuration.
  • Size: 2.0 KB, SHA1 d95815c367e0
Hashes and source
required for Acorn BBC Master 128 missing standalone installed with the standalone emulator MD5 83d73e0e7869

TUBE110.rom

6502 TUBE 1.10 (6502 Second Processor)

  • Standalone path: assets/roms/TUBE110.rom
  • System: Acorn BBC Micro Model B
  • Second processor OS ROM, read only by configurations with that parasite. A failed load, or an image over 4 KiB, aborts loading the configuration.
Hashes and source
required for Acorn BBC Micro Model B in repo standalone installed with the standalone emulator MD5 a77c7946128c

mos.rom

MOS 3.20 MOS (OS)

  • Standalone path: assets/roms/m128/3.20/mos.rom
  • System: Acorn BBC Master 128
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 04d5876999f9
Hashes and source
required for Acorn BBC Master 128 missing standalone installed with the standalone emulator MD5 9087f7724470

mos.rom

MOS 3.50 MOS (OS)

  • Standalone path: assets/roms/m128/3.50/mos.rom
  • System: Acorn BBC Master 128
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 3b6f5a82a458
Hashes and source
required for Acorn BBC Master 128 missing standalone installed with the standalone emulator MD5 d7a046b1e6a9

mos.rom

MOS 5.00 MOS (OS)

  • Standalone path: assets/roms/mcompact/5.00/mos.rom
  • System: Acorn BBC Master Compact
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 8720284aafa2
Hashes and source
required for Acorn BBC Master Compact missing standalone installed with the standalone emulator MD5 5d1b635e39aa

mos.rom

MOS 5.10 MOS (OS)

  • Standalone path: assets/roms/mcompact/5.10/mos.rom
  • System: Acorn BBC Master Compact
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 844b056bcfb4
Hashes and source
required for Acorn BBC Master Compact missing standalone installed with the standalone emulator MD5 f65eb89c7044

mos.rom

MOS I5.10C MOS (OS)

  • Standalone path: assets/roms/mcompact/I5.10C/mos.rom
  • System: Acorn BBC Master Compact
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 736561de7010
Hashes and source
required for Acorn BBC Master Compact missing standalone installed with the standalone emulator MD5 5e16a38bd7fd

mos.rom

MOS 5.11i MOS (OS)

  • Standalone path: assets/roms/mcompact/5.11i/mos.rom
  • System: Acorn BBC Master Compact
  • OS ROM of the configurations that select it. A failed load, or an image over 16 KiB, aborts loading the configuration, while a shorter image is placed at the top of the 16 KiB window.
  • Size: 16.0 KB, SHA1 4db54c0427f6
Hashes and source
required for Acorn BBC Master Compact missing standalone installed with the standalone emulator MD5 e0da72786377

Optional

Section titled “Optional”
34 rows
FileStatusHash

BASIC2.ROM

BASIC II

  • Standalone path: assets/roms/BASIC2.ROM
  • System: Acorn BBC Micro Model B
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
Hashes and source
in repo standalone installed with the standalone emulator MD5 2cc67be4624d

DFS-2.26.rom

Acorn 1770 DFS

  • Standalone path: assets/roms/DFS-2.26.rom
  • System: Acorn BBC Micro Model B
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
Hashes and source
in repo standalone installed with the standalone emulator MD5 f083f49d6fe6

DDFS-1.53.rom

Watford DDFS (DDB2)

  • Standalone path: assets/roms/DDFS-1.53.rom
  • System: Acorn BBC Micro Model B
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
Hashes and source
in repo standalone installed with the standalone emulator MD5 d2b71fa664f6

DDFS-1.54T.rom

Watford DDFS (DDB3)

  • Standalone path: assets/roms/DDFS-1.54T.rom
  • System: Acorn BBC Micro Model B
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 618b7a1551f9
Hashes and source
missing standalone installed with the standalone emulator MD5 e73a04172785

OPUS-DDOS-3.45.rom

Opus DDOS

  • Standalone path: assets/roms/OPUS-DDOS-3.45.rom
  • System: Acorn BBC Micro Model B
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 1c5a68e08abb
Hashes and source
missing standalone installed with the standalone emulator MD5 d98316eaff56

challenger-1.01.rom

Opus Challenger

  • Standalone path: assets/roms/challenger-1.01.rom
  • System: Acorn BBC Micro Model B
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 37ee3f20bed5
Hashes and source
missing standalone installed with the standalone emulator MD5 67e086a11834

dfs.rom

MOS 3.20 DFS (9)

  • Standalone path: assets/roms/m128/3.20/dfs.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 cff80460954b
Hashes and source
missing standalone installed with the standalone emulator MD5 865a0f7a5d6f

viewsht.rom

MOS 3.20 Viewsheet (a)

  • Standalone path: assets/roms/m128/3.20/viewsht.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 b7e85a55f517
Hashes and source
missing standalone installed with the standalone emulator MD5 7d5a80a8ce92

edit.rom

MOS 3.20 Edit (b)

  • Standalone path: assets/roms/m128/3.20/edit.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 96d209441f4c
Hashes and source
missing standalone installed with the standalone emulator MD5 cb3d762eaab6

basic4.rom

MOS 3.20 BASIC (c)

  • Standalone path: assets/roms/m128/3.20/basic4.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
Hashes and source
in repo standalone installed with the standalone emulator MD5 63a6f43cbf49

adfs.rom

MOS 3.20 ADFS (d)

  • Standalone path: assets/roms/m128/3.20/adfs.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 7557e99be10d
Hashes and source
missing standalone installed with the standalone emulator MD5 10f08b255d6a

view.rom

MOS 3.20 View (e)

  • Standalone path: assets/roms/m128/3.20/view.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 14820174e8ea
Hashes and source
missing standalone installed with the standalone emulator MD5 178d09285727

terminal.rom

MOS 3.20 Terminal (f)

  • Standalone path: assets/roms/m128/3.20/terminal.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 d990f41a3a06
Hashes and source
missing standalone installed with the standalone emulator MD5 7e053353b78b

dfs.rom

MOS 3.50 DFS (9)

  • Standalone path: assets/roms/m128/3.50/dfs.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 0a1cc8747e49
Hashes and source
missing standalone installed with the standalone emulator MD5 22c2b7f14f24

viewsht.rom

MOS 3.50 Viewsheet (a)

  • Standalone path: assets/roms/m128/3.50/viewsht.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 7e97cd3539ab
Hashes and source
missing standalone installed with the standalone emulator MD5 1bc68b7c5eba

edit.rom

MOS 3.50 Edit (b)

  • Standalone path: assets/roms/m128/3.50/edit.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 85519afe983a
Hashes and source
missing standalone installed with the standalone emulator MD5 8c72c7f24567

basic4.rom

MOS 3.50 BASIC (c)

  • Standalone path: assets/roms/m128/3.50/basic4.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 8e9d3eeba379
Hashes and source
missing standalone installed with the standalone emulator MD5 e11eed95d1ca

adfs.rom

MOS 3.50 ADFS (d)

  • Standalone path: assets/roms/m128/3.50/adfs.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 c81cf13f11d9
Hashes and source
missing standalone installed with the standalone emulator MD5 fb8ceb72c5fb

view.rom

MOS 3.50 View (e)

  • Standalone path: assets/roms/m128/3.50/view.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 313a248dadcd
Hashes and source
missing standalone installed with the standalone emulator MD5 1566fab2f182

terminal.rom

MOS 3.50 Terminal (f)

  • Standalone path: assets/roms/m128/3.50/terminal.rom
  • System: Acorn BBC Master 128
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 4ca97b439e8b
Hashes and source
missing standalone installed with the standalone emulator MD5 b1fa51fd49d3

adfs.rom

MOS 5.00 ADFS (d)

  • Standalone path: assets/roms/mcompact/5.00/adfs.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 e5b6988ada09
Hashes and source
missing standalone installed with the standalone emulator MD5 bfbd0a7dbbfb

basic4.rom

MOS 5.00 BASIC (e)

  • Standalone path: assets/roms/mcompact/5.00/basic4.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 2278018884c6
Hashes and source
missing standalone installed with the standalone emulator MD5 64b3cd52e36b

utils.rom

MOS 5.00 UTILS (f)

  • Standalone path: assets/roms/mcompact/5.00/utils.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 b8ebb39e6373
Hashes and source
missing standalone installed with the standalone emulator MD5 4f9ded16f442

adfs.rom

MOS 5.10 ADFS (d)

  • Standalone path: assets/roms/mcompact/5.10/adfs.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 a080fff109e1
Hashes and source
missing standalone installed with the standalone emulator MD5 c2afc1cabb13

basic4.rom

MOS 5.10 BASIC (e)

  • Standalone path: assets/roms/mcompact/5.10/basic4.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 2278018884c6
Hashes and source
missing standalone installed with the standalone emulator MD5 64b3cd52e36b

utils.rom

MOS 5.10 UTILS (f)

  • Standalone path: assets/roms/mcompact/5.10/utils.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 8134476d8850
Hashes and source
missing standalone installed with the standalone emulator MD5 48a197850113

adfs.rom

MOS I5.10C ADFS (d)

  • Standalone path: assets/roms/mcompact/I5.10C/adfs.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 222a4c73e314
Hashes and source
missing standalone installed with the standalone emulator MD5 10f23a239dde

basic4.rom

MOS I5.10C BASIC (e)

  • Standalone path: assets/roms/mcompact/I5.10C/basic4.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 261023c99952
Hashes and source
missing standalone installed with the standalone emulator MD5 717df34edae5

utils.rom

MOS I5.10C UTILS (f)

  • Standalone path: assets/roms/mcompact/I5.10C/utils.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 5ace7ba3e329
Hashes and source
missing standalone installed with the standalone emulator MD5 75364aa6fd5e

adfs.rom

MOS 5.11i ADFS (d)

  • Standalone path: assets/roms/mcompact/5.11i/adfs.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 03b536e0dfcb
Hashes and source
missing standalone installed with the standalone emulator MD5 ce15d43fe56f

basic4.rom

MOS 5.11i BASIC (e)

  • Standalone path: assets/roms/mcompact/5.11i/basic4.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 f9f9d7658d50
Hashes and source
missing standalone installed with the standalone emulator MD5 48c5b544025e

utils.rom

MOS 5.11i UTILS (f)

  • Standalone path: assets/roms/mcompact/5.11i/utils.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 28eb171c8ea2
Hashes and source
missing standalone installed with the standalone emulator MD5 27aaeace0cce

arabic.rom

MOS 5.11i ARABIC (usually 8)

  • Standalone path: assets/roms/mcompact/5.11i/arabic.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 2bbf61ba6826
Hashes and source
missing standalone installed with the standalone emulator MD5 64e7627ef99a

international.rom

MOS 5.11i INTERNATIONAL (usually 2)

  • Standalone path: assets/roms/mcompact/5.11i/international.rom
  • System: Acorn BBC Master Compact
  • Sideways ROM bank of the configurations that select it. A failed load is reported and the configuration loads with the bank empty.
  • Size: 16.0 KB, SHA1 dc5149ccf588
Hashes and source
missing standalone installed with the standalone emulator MD5 881baf661c61

Next steps

Section titled “Next steps”
.

Maintained by Abdess on GitHub. Report a problem.

Packs from release v2026.10.10, .

MIT for the tooling and metadata. BIOS and firmware files are third-party system software, preserved for personal backup, archival and interoperability.