JollyCV - RetroBIOS¶
Platform details
colecovision: - bios_filename: coleco.rom - bios_size: 8192 - memory_map: 0x0000-0x1FFF - source_ref: src/jcv_coleco.c:269-281 creativision: - bios_filename: bioscv.rom - bios_size: 2048 - memory_map: 0xF800-0xFFFF - source_ref: src/jcv_crvision.c:315-337, 441 myvision: - bios_required: False - note: No BIOS needed. My Vision games run without any system ROM.
Technical notes
JollyCV is a multi-system emulator by Rupert Carmichael supporting ColecoVision (with Super Game Module), CreatiVision, and My Vision.
BIOS handling depends on the detected system type (set via core option or auto-detected from ROM database via jcv_process_hash/jcv_get_dbflags):
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ColecoVision (JCV_SYS_COLECO): loads "coleco.rom" from system dir. BIOS is mapped at 0x0000-0x1FFF. Size must be exactly 8192 bytes (SIZE_CVBIOS = SIZE_8K = 0x2000). Load fails if size mismatches. Without the BIOS, ColecoVision games will not run (load returns false).
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CreatiVision (JCV_SYS_CRVISION): loads "bioscv.rom" from system dir. BIOS is mapped at 0xF800-0xFFFF. Size must be exactly 2048 bytes (SIZE_CRVBIOS = SIZE_2K = 0x800). Without the BIOS, CreatiVision games will not run.
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My Vision (JCV_SYS_MYVISION): no BIOS required.
The libretro port constructs paths via snprintf("%s%c%s", sysdir, pss, filename) in libretro.c:699-711. jcv_bios_load_file() opens the file, reads it fully, then delegates to jcv_coleco_bios_load() or jcv_crvision_bios_load() which validate size before copying.
ColecoVision cartridge header bytes at offset 0x0000-0x0001 control boot behavior: 0xAA55 shows the BIOS title screen, 0x55AA jumps directly to the game code vector.
The core includes a built-in ROM database with MD5 hashes (gamedb.h) for game-specific flags, but this is for game compatibility, not BIOS verification.
2 files | 2 required, 0 optional | 2 in repo, 0 missing
coleco.rom required in repo
bioscv.rom required in repo
VTech CreatiVision BIOS ROM
Generated on 2026-04-18T08:05:07Z