$ show MockbaTheBorg/RunCPM
RunCPM is a Z80 CPU and CP/M emulator that executes unmodified 8-bit CP/M application binaries on desktop operating systems and embedded microcontrollers. The code provides a complete Z80 instruction-set emulation (selectable among four CPU models), a CP/M 2.2/3 BDOS and BIOS dispatcher, a built-in CCP console command processor, and a host-directory-to-CP/M-drive mapping. Desktop entry points are RunCPM/main.c; embedded entry points are in RunCPM/RunCPM.ino, with board-specific hardware definitions for Arduino, Teensy, ESP32, STM32, and RP2040. CP/M disk drives are folders on the host filesystem, and user areas are numbered subdirectories. External dependencies are limited to platform C libraries, optional SDL/RunVT terminal integration, and SD-card filesystem support on embedded targets. Custom BDOS calls allow CP/M programs to control physical GPIO pins on supported boards.
The LLM identified 4 files worth highlighting for reuse:
A high-performance Z80 CPU core using algorithmic x/y/z/p/q opcode decoding and GCC computed gotos for dispatch. It uses precomputed flag tables and cycle timing to emulate the full Z80 instruction set efficiently. This is the most reusable standalone component: with minimal adaptation it could serve as the CPU engine in another Z80 emulator, test harness, or toolchain project.
A complete Z80 debugger embedded in the emulator: instruction disassembly, trace buffer, breakpoints, watchpoints, and memory dump facilities. It is self-contained and demonstrates non-obvious systems-programming skill. It could be extracted and reused in any Z80 emulator or reverse-engineering tool.
The CP/M BDOS and BIOS implementation with support for CP/M 2.2 and conditionally compiled CP/M 3 features, including file operations, DMA management, and a CP/M-style console line editor with control-key handling. This is the core system-call layer that makes the emulator CP/M-compatible and is reusable for anyone building a CP/M-compatible runtime or testing CP/M programs.
A banked RAM emulation layer with fast-path macros for non-banked configurations and slower function calls for banked memory. It cleanly isolates memory layout and banking from the CPU and CP/M layers, making it a small, reusable memory model for Z80/CP/M emulators.