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PC-9800

PC-9800 icon PC-9800 logo

Overview

NEC’s PC-9800 series launched in 1982 and became Japan’s staple 16/32-bit home computer, spawning a massive library of visual novels, shmups and PC-exclusive adventures. REG-Linux maps the platform to pc98 so metadata and theme packs can highlight the correct imagery.

Quick reference

  • ROM folder: /userdata/roms/pc98
  • Accepted formats: .d98, .zip, .98d, .fdi, .fdd, .2hd, .tfd, .d88, .88d, .hdm, .xdf, .dup, .cmd, .hdi, .thd, .nhd, .hdd, .hdn, .m3u
  • Emulator: libretro: np2kai
  • System group: pc98

Technical specifications

  • CPU: NEC V20/V30 family (8086/80186 compatible) running between 5 and 10 MHz, depending on the model.
  • Memory: Starts at 256 KB and scales to 640 KB plus optional expansion boards with several megabytes of RAM.
  • Display: Dual NEC µPD7220 video chips enabling 640×400 color modes or 1024×1024 monochrome with high-resolution text.
  • Sound: Yamaha YM2203 with later models adding mu-law PCM chips for richer audio and music.

BIOS

Copy the following BIOS assets into /userdata/bios/np2kai/ before launching games. np2kai reads them to match the emulated hardware:

MD5 checksum Filename Notes
e246140dec5124c5e404869a84caefce BIOS.ROM Core PC-98 BIOS
2af6179d7de4893ea0b705c00e9a98d6 FONT.ROM Optional font ROM
caf90f22197aed6f14c471c21e64658d SOUND.ROM Legacy sound ROM
e9fc3890963b12cf15d0a2eea5815b72 ITF.ROM International font ROM
7da1e5b7c482d4108d22a5b09631d967 font.bmp Raster font bitmap

Drop additional assets (PC-9821 BIOS, YM2608 waveforms, etc.) into the same folder and np2kai will load them automatically.

ROMs

Put all PC-98 disk and hard-drive images inside /userdata/roms/pc98. Hard-drive images (.hdi, .hdm, .nhd, .2hd, etc.) are usually the easiest to boot; they contain a preconfigured system. Floppy-based releases (.fdi, .d98, .d88, etc.) can stay in the same directory—np2kai prompts for each disk as needed. For raw CDs, convert the contents into a hard-drive image before playing.

Emulators

RetroArch

RetroArch hosts the libretro: np2kai core. Use [HOTKEY] + the south face button to open the Quick Menu for shaders, overrides and controller bindings. EmulationStation exposes common options such as pc98.gfxbackend, pc98.audio_latency and pc98.video_threaded.

libretro: np2kai

np2kai lets you tune the emulated machine via:

  • global.np2kai_model: choose between modern PC-286/PC-9801 variants.
  • global.np2kai_cpu_feature: pick from 386 through Pentium-class processors.
  • global.np2kai_clk_mult: adjust the internal multiplier (6x recommended, but lower values help older software).
  • global.np2kai_ExMemory: add up to 1 GB of RAM for RAM-intensive titles.
  • global.np2kai_gdc: switch between uPD7220/uPD72020 Graphics Display Controllers.
  • global.np2kai_skipline: remove scanlines when desired.
  • global.np2kai_realpal: enable the real palette required by a handful of games (e.g., Apro).
  • global.np2kai_SNDboard: match the original audio board (PC9801-14, PC9801-86, Sound Blaster 16, etc.).
  • global.np2kai_jast_snd: activate richer JAST sound formats.
  • global.np2kai_joymode: map joystick buttons to keyboard input when needed.

GDC clock notes

If a title displays duplicated or flickering text, enter the BIOS menu (hold [End] during boot or [HOTKEY] + east to reopen), navigate to Dip Switch 2 (ディップスイッチ２), and set the GDC clock to 2.5 MHz; many compatibility issues disappear when the correct clock is selected.

Controls

The overlay at ../images/controller-overlays/pc98.png mirrors the PC-98 keyboard layout so you can trigger shortcuts and function keys directly from the controller.

Troubleshooting

  • Make sure every BIOS file lives in /userdata/bios/np2kai/ with the correct filenames.
  • If a game refuses to boot, try a different image type (hard drive vs floppy) or reduce the CPU multiplier.
  • Visit the generic support pages for broader assistance.