6809 CPU Emulator project started

CpuEmulator is a CPU emulator project that aims to emulate a CPU (the 6809 to start with), it’s registers, and system memory. It will allow you to monitor registers, flags and memory as you step through code. Having done SharpiEmu for the Sharp PC–1360 Pocket Computer, the concept seems pretty simple. The 6809 has a number of addressing modes, and different opcodes for the same mnemonic. So I’m expecting it to be somewhat more of a challenge.

Initial version will emulate the CPU, memory, and text video mode.


  • Emulate 6809 instructions
  • Emulate 32×16 & 80×24 text modes
  • Emulate the Coco3’s MMU
  • 4K all the way up to 512KB memory options
  • Debugger that steps through code, shows current state of registers, selected memory block, and source code from a listing file.
  • Break points. They are remembered between runs.
  • Memory watcher. When memory at a certain addresses are modified, a breakpoint is triggered so you can see what modified it.

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