PD777 - RetroBIOS

Type	libretro
Source	https://github.com/W88DodPECuThLOl/PD777
Version	v1.0.0
Profiled	2026-03-18
Cores	pd777
Systems	epochcv

No BIOS or firmware files required. This core is self-contained.

PD777 is an Epoch Cassette Vision emulator (NEC uPD777C CPU) with a libretro interface, by W88DodPECuThLOl.

No BIOS or firmware files required. The .info file declares firmware_count = 0.

Game loading in source/libretro/libretro.cpp:retro_load_game() (line 386-474). The core loads a code ROM file (.bin777) directly from the content path, then attempts to load a pattern ROM file (.ptn777) by replacing the extension.

If neither file is found, the core falls back to hardcoded ROM data compiled from source/core/rom.cpp (Battle Vader program + pattern ROM dumps from oguchi-rd.com).

The code ROM supports three formats: - Raw order: exactly 0xF00 bytes, program words in sequential address order - Raw address: address/data pairs (compiled-in rawRom[] array) - Formatted: header starting with "_CassetteVision_000" magic, version 0 or 1, includes key mapping, title, and code section at offset 0x100

The pattern ROM supports three formats: - Formatted: 0x340 bytes, header "CassetteVision0000", 7x7 + 8x7 CG patterns - Raw bitstream: 0x4D0 bytes, bit-packed 7x7 and 8x7 character patterns - Built-in: fallback to patternRom[] / patternRom8[] arrays in rom.cpp

The system directory path is retrieved via RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY but is not used for any file loading.

Game identification uses a checksum over the loaded ROM to detect known cassettes (Battle Vader, Galaxian, etc.) and apply per-game key mappings and bent character tables. 11 cassette IDs are recognized (1-9, 11, 12).

Supported extensions: zip, bin777, ptn777.

Generated on 2026-03-20T19:12:20Z