PicoDrive - RetroBIOS¶


Type	libretro
Classification	Official ports
Source	https://github.com/libretro/picodrive
Upstream	https://github.com/irixxxx/picodrive
Version	1.99
Profiled	2026-03-24
Cores	picodrive
Systems	sega-megadrive, sega-genesis, sega-megacd, sega-segacd, sega-32x, sega-mastersystem, sega-gamegear, sega-sg1000, sega-sc3000, sega-pico

Platform details

megacd: - bios_size: 131072 - hle_available: False - region_specific: True - extensions_tried: ['.bin', '.zip'] - source_ref: pico/pico_int.h:559, platform/libretro/libretro.c:1309-1317 32x: - m68k_bios_size: 256 - master_sh2_bios_size: 2048 - slave_sh2_bios_size: 1024 - hle_available: True - source_ref: pico/pico.h:54-55, pico/pico_int.h:679-693 sms: - hle_available: True - note: No BIOS file loaded. VDP/RAM initialized to post-BIOS state. - source_ref: pico/sms.c:1080-1097

Technical notes

PicoDrive is a fast Mega Drive / Genesis emulator with Mega CD, 32X, Master System, Game Gear, SG-1000, SC-3000 and Sega Pico support. The libretro port is part of the PicoDrive source tree (platform/libretro/).

Mega CD / Sega CD games require a region-matching BIOS file. The core searches the system directory for each name in order, trying .bin then .zip extension, and uses the first file found. If no BIOS is found, CD games fail to load with PM_BAD_CD_NO_BIOS. MSU-MD games can run without BIOS.

BIOS filename search order (platform/libretro/libretro.c:1264-1328): US: us_scd2_9306, SegaCDBIOS9303, us_scd1_9210, bios_CD_U EU: eu_mcd2_9306, eu_mcd2_9303, eu_mcd1_9210, bios_CD_E JP: jp_mcd2_921222, jp_mcd1_9112, jp_mcd1_9111, bios_CD_J

32X BIOS files (m68k, master SH2, slave SH2) are fully optional. The engine has built-in HLE that generates replacement code at startup when the BIOS pointers are NULL (pico/32x/memory.c:2200 get_bios(), pico/32x/32x.c:172). No current frontend (libretro or standalone) loads these files; the standalone loading code is disabled (#if 0 in platform/common/emu.c:1529).

carthw.cfg is a cartridge hardware database loaded from the system directory. A built-in version is compiled into the core (pico/carthw_cfg.c). The external file supplements or overrides game-specific hardware detection (SVP, EEPROM types, special mappers, copy protection).

Master System, Game Gear, SG-1000, SC-3000: no BIOS file loaded. The core initializes VDP registers and RAM to simulate post-BIOS state (pico/sms.c:1080-1097).

16 files | 3 required, 13 optional | 16 in repo, 0 missing | 3 with HLE fallback

carthw.cfg optional in repo

Source: platform/libretro/libretro.c:1619, pico/cart.c:1020-1022
Cartridge hardware database for special mapper and EEPROM detection. Built-in fallback compiled into the core.

us_scd2_9306.bin required in repo north-america

System: sega-segacd
Size: 128.0 KB
Priority: 1
Source: platform/libretro/libretro.c:1265
US Sega CD Model 2 BIOS (September 1993). First in US search order.

SegaCDBIOS9303.bin optional in repo north-america

System: sega-segacd
Size: 128.0 KB
Priority: 2
Source: platform/libretro/libretro.c:1265
US Sega CD BIOS (March 1993). Second in US search order.

us_scd1_9210.bin optional in repo north-america

System: sega-segacd
Size: 128.0 KB
Priority: 3
Source: platform/libretro/libretro.c:1265
US Sega CD Model 1 BIOS (October 1992). Third in US search order.

bios_CD_U.bin optional in repo north-america

System: sega-segacd
Size: 128.0 KB
Priority: 4
Source: platform/libretro/libretro.c:1265
Platforms: batocera, emudeck, lakka, recalbox, retroarch, retrobat, retrodeck, retropie, rocknix, romm
US Sega CD BIOS (generic name). Last in US search order.

eu_mcd2_9306.bin required in repo europe

System: sega-megacd
Size: 128.0 KB
Priority: 1
Source: platform/libretro/libretro.c:1268
EU Mega CD Model 2 BIOS (June 1993). First in EU search order.

eu_mcd2_9303.bin optional in repo europe

System: sega-megacd
Size: 128.0 KB
Priority: 2
Source: platform/libretro/libretro.c:1268
EU Mega CD Model 2 BIOS (March 1993). Second in EU search order.

eu_mcd1_9210.bin optional in repo europe

System: sega-megacd
Size: 128.0 KB
Priority: 3
Source: platform/libretro/libretro.c:1268
EU Mega CD Model 1 BIOS (October 1992). Third in EU search order.

bios_CD_E.bin optional in repo europe

System: sega-megacd
Size: 128.0 KB
Priority: 4
Source: platform/libretro/libretro.c:1268
Platforms: batocera, emudeck, lakka, recalbox, retroarch, retrobat, retrodeck, retropie, rocknix, romm
EU Mega CD BIOS (generic name). Last in EU search order.

jp_mcd2_921222.bin required in repo japan

System: sega-megacd
Size: 128.0 KB
Priority: 1
Source: platform/libretro/libretro.c:1271
JP Mega CD Model 2 BIOS (December 1992). First in JP search order.

jp_mcd1_9112.bin optional in repo japan

System: sega-megacd
Size: 128.0 KB
Priority: 2
Source: platform/libretro/libretro.c:1271
JP Mega CD Model 1 BIOS (December 1991). Second in JP search order.

jp_mcd1_9111.bin optional in repo japan

System: sega-megacd
Size: 128.0 KB
Priority: 3
Source: platform/libretro/libretro.c:1271
JP Mega CD Model 1 BIOS (November 1991). Third in JP search order.

bios_CD_J.bin optional in repo japan

System: sega-megacd
Size: 128.0 KB
Priority: 4
Source: platform/libretro/libretro.c:1271
Platforms: batocera, emudeck, lakka, recalbox, retroarch, retrobat, retrodeck, retropie, rocknix, romm
JP Mega CD BIOS (generic name). Last in JP search order.

32X_G_BIOS.BIN optional in repo HLE fallback

System: sega-32x
Size: 256 B
Source: pico/32x/memory.c:2206-2243
Platforms: bizhawk, retrobat, retrodeck
32X 68K (Genesis-side) BIOS. HLE replacement generated when NULL.

32X_M_BIOS.BIN optional in repo HLE fallback

System: sega-32x
Size: 2.0 KB
Source: pico/32x/memory.c:2249-2276
Platforms: bizhawk, retrobat, retrodeck
32X Master SH2 BIOS. HLE replacement generated when NULL.

32X_S_BIOS.BIN optional in repo HLE fallback

System: sega-32x
Size: 1.0 KB
Source: pico/32x/memory.c:2279-2297
Platforms: bizhawk, retrobat, retrodeck
32X Slave SH2 BIOS. HLE replacement generated when NULL.

Generated on 2026-09-14T09:03:10Z