emulator: EmuSCV
type: libretro
core_classification: community_fork
source: "https://github.com/wzcwzc/emuscv"
upstream: "http://takeda-toshiya.my.coocan.jp/"
profiled_date: "2026-03-23"
source_commit: "6d6e4594d79862dd5c2ff7f725c109e4266f0b03"
core_version: "0.12.20220726135800"
version_basis:
  kind: file
  path: "Makefile.libretro"
  pattern: '^EMUSCV_VERSION_MAJOR := (\d+)\s*\nEMUSCV_VERSION_MINOR := (\d+)\s*\n(?:#.*\n)*EMUSCV_VERSION_DATETIME := \u0027?(\d+)'
  format: "{1}.{2}.{3}"
display_name: "EPOCH/YENO Super Cassette Vision"
cores:
  - emuscv
systems:
  - scv

notes: |
  Libretro port of eSCV by Takeda Toshiya (Common Source Code Project),
  ported to libretro by MARCONATO Maxime. Upstream source mirrored at
  https://github.com/tautologico/common-src-project (src/vm/scv/).

  BIOS loading in src/vm/scv/memory.cpp:initialize() (lines 74-243).
  Tries filenames in order: upd7801g.s01, upd7801g.bin, upd7801g.bios,
  bios.rom, bios.bin. First successful open wins. Upstream eSCV uses
  only BIOS.ROM (uppercase), and the libretro port renamed and added
  fallback aliases.

  The BIOS is read as 0x1000 (4096) bytes into the bios[] array, mapped
  read-only at CPU address 0x0000-0x0FFF (UPD7801 internal ROM area).

  When CHECKBIOS core option is YES, the core computes MD5 of the loaded
  data and compares against 635a978fd40db9a18ee44eff449fc126. If the
  hash does not match, the BIOS is rejected (filled with 0xFF,
  bios_present=false). When CHECKBIOS is AUTO (default) or NO, any file
  content is accepted. With AUTO the log says "automatic (yes)", and the
  MD5 comparison runs only when the option equals YES_VAL
  (src/vm/scv/memory.cpp:80), so AUTO accepts any content.

  The font/character data is embedded within the BIOS at offset 0x200
  (memory.h get_font() returns bios + 0x200). No separate font ROM file.

  The core can start without BIOS (supports_no_game=true) but shows
  "BIOS not found" or "Bad BIOS" on the OSD. Games will not run without
  it.

  The .info declares firmware_count=1, firmware0_opt=false. Matches code.

files:
  - name: "upd7801g.s01"
    system: scv
    required: true
    size: 4096
    md5: 635a978fd40db9a18ee44eff449fc126
    validation: [md5]
    note: "UPD7801G internal ROM (BIOS). Mapped at 0x0000-0x0FFF. Contains character font at offset 0x200."
    source_ref: "src/vm/scv/memory.cpp:74-243"
    aliases:
      - "upd7801g.bin"
      - "upd7801g.bios"
      - "bios.rom"
      - "bios.bin"

platform_details:
  cpu: "NEC UPD7801G"
  bios_mapping:
    upd7801g:
      target: "0x0000-0x0FFF (CPU internal ROM, 4 KB)"
      format: "raw binary"
      source_ref: "src/vm/scv/memory.cpp:249-254"
      notes: |
        Memory map from memory.cpp:initialize():
          0x0000-0x0FFF  BIOS ROM (read-only)
          0x2000-0x3FFF  VRAM (8 KB)
          0x8000-0xFF7F  Cartridge ROM (up to 4 banks of 32 KB)
          0xFF80-0xFFFF  CPU internal RAM (128 bytes)
        Font data lives inside the BIOS at offset 0x200, accessed via
        get_font() for the VDP character rendering (src/vm/scv/vdp.cpp).

  cartridge_loading:
    formats: "cart, bin, rom, 0 (multi-file: .0/.1/.2/.3), zip"
    banking: "4 banks of 32 KB via PC5/PC6 port lines"
    source_ref: "src/vm/scv/memory.h, src/vm/scv/memory.cpp"