mnemonic

js68xkjit — a 68k CPU and test computer platform in Node.js.

Originally built around the j68 CPU core created by Takashi Toyoshima https://github.com/toyoshim/j68k

This project has since grown into a broader bring-up, monitor, test, and CPU validation platform around that base. A small virtual Motorola 68k test computer built around the j68k CPU core and now includes Audio playback, video is next on the menu

This project is a bring-up machine, not a full Amiga implementation. The focus is:

• reset and vector behavior
• ROM/RAM/MMIO integration
• UART-backed machine-code monitor
• small guest programs loaded from the monitor
• deterministic system tests around exceptions, IRQs, and monitor workflows

Current project shape:

• src/j68.js
  • CPU core
• src/machine/
  • machine, bus, memory map, devices
• src/monitor/
  • monitor shell, tiny assembler/disassembler, commands
• rom/
  • monitor and test ROMs
• source/
  • monitor-loadable assembly source for loadasm
• save/
  • compiled binaries and saved monitor artifacts
• work/programs/
  • host-assembled standalone 68k programs and guest-side helper libraries
• test/system/
  • machine and monitor integration tests

Quick start:

./runtests.sh
cd test && node runner.js
node tools/monitor.js

Build/run flow:

• default CPU runner uses cached test/r/*.r artefacts and rebuilds only missing outputs:

  cd test && node runner.js

• explicit source rebuild path for CPU tests:

  cd test && node runner.js --from-source

• explicit clean + full CPU test rebuild:

  cd test && node runner.js --clean --rebuild-all

• direct CPU test artefact maintenance:

  cd test && node build.js --rebuild-missing
  cd test && node build.js --rebuild-all
  cd test && node build.js --clean --rebuild-all

• monitor startup uses cached generated ROM binaries by default:

  node tools/monitor.js

• explicit monitor ROM rebuild from source:

  node tools/monitor.js --from-source

Generated ROM binaries are cached under build/generated/m68k/.

Typical monitor flow:

list
load 00090000 puthex.bin
g 00090000

source
loadasm 00090000 helloworld.asm
g 00090000

Environment:

• J68_CPU_TYPE
  • default: 68000
• J68_CHIP_RAM_SIZE
  • default comes from TestMachine
• J68_FAST_RAM_SIZE
  • default comes from TestMachine
• M68K_AS
• M68K_OBJCOPY

Current stable baseline:

• ./runtests.sh stays green

• cd test && node runner.js stays 231/233

• CALLM and RTM remain explicitly deferred

• Passed: 231/233

• Failed: 0/231

• Deferred: 2/233

deferred invalid smoke test: 2

r/callm.r [deferred invalid smoke test]: CALLM requires a valid module descriptor and transfer target; this local smoke test points A0 at the program image r/rtm.r [deferred invalid smoke test]: RTM requires a saved module state on the stack from a prior CALLM

Audio

Yes we can now play Audio, its a little choppy and raw however this is a machine code demo, its not polished

./startmonitor.sh
j68
j68> loadasm 00090000 axelf.asm
j68> g 00090000

Is that not Axel F and is that not just fitting for a 68000 CPU