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.