Lua 5.3 didn't need an x86 emulator. But now, it has one regardless.
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Barely-IBM-compatible PC emulator written in Lua 5.3.

Compilation Instructions

  1. Run ./ on a (preferably?) Linux machine.
  2. Edit disks.lua to point to your disk images.
  3. Run platform_oc.lua in OpenComputers or Kallisti, or platform.lua with lcurses (text mode only).

What’s Emulated?

Probably decently

  • CPU: 8086-esque
  • Graphics: CGA (640x200x1, 320x200x2, text modes), 320x200x8 (Mode 13h)
    • With some partial I/O ports emulation!
  • BIOS: High-level emulation
    • Decent implementations of most expected interrupts


  • Audio: PC Speaker (Computronics Beep Card)
  • Keyboard: PC XT-compatible
  • 8259 PIC
  • 8253 PIT

Not even tested

  • Graphics: Tandy-compatible

Not even implemented

  • BIOS: Serial/Printer Port interrupts, INT 15h
  • Pretty much anything not listed


  • platform.lua outputs debug text to stderr. Run with “2>/dev/null” to avoid.
  • The performance on my desktop (i7-4790K) seems to be:
    • about 3x PC XT in Lua 5.3,
    • about 0.6x PC XT in latest stable OpenComputers,
    • about 1x PC XT in latest stable OpenComputers + fixed machine.lua - you may override it server-side,
    • about 1.8x PC XT in latest stable OpenComputers + fixed machine.lua + natives recompiled to actually use -O2 and not debug mode,
    • about 2.5x PC XT in Kallisti with the timeout-checking code disabled altogether, and about 1.8x PC XT otherwise.
  • There’s a lot of bugs and hacks.

Known issues

Many. See the Wiki for the Compatibility List.

In particular, a “reduced memory usage” mode has to be introduced for OC users.


TBD. For now, consider it “all rights reserved” - or just ask on IRC.


  • 8086tiny, for providing the initial motivation and being one of the emulators which proved helpful during development
  • Publicly available 8086 test suites used: