CP/M Emulator

A CP/M 2.2 operating system emulator that runs legacy 8-bit CP/M applications on modern systems. Features both Intel 8080 and Zilog Z80 CPU emulation with comprehensive BDOS/BIOS support.

Supported Platforms: Linux (x64, ARM64) and Windows (x64)

cpmemu emulates BIOS and BDOs calls and translates them to Unix. Most emulators have a file on the OS containing a native CP/M file system. Then, when testing a compiler, it is necessary to import programs to the CP/M disk and export test run results. With cpmemu, all the files can be stored in the linux file system, which is more convenient to manage.

This translated file io emulator idea is not new. The tnylpo package https://github.com/SvenMb/gbrein_tnylpo has been doing it since 2018. However, tnylpo only works well with filenames that fit the 8.3 format. Also, tnylpo comes with a conversion program to handle the EOL conversions.

cpmemu allows mapping files anywhere in the linux file system of any length with any characters into a fake 8.3 CP/M name. This allows better naming of compiler test suite programs. Also, a config file can be supplied for the file name mapping and type (text vs binary) for each file.

Features

Dual CPU modes: Intel 8080 (default) and Zilog Z80 instruction sets
CP/M environment: BDOS file/console functions and BIOS character I/O
File I/O translation: Maps CP/M file operations to Unix filesystem
Text/binary mode: Automatic EOL conversion between CP/M and Unix
Device redirection: Printer and auxiliary I/O device support
Configuration files: Support for complex setups and file mappings
^C handling: Ctrl+C passes through to CP/M programs (e.g., to interrupt BASIC); press 5 times consecutively to exit emulator

Installation

Windows

Download and install the MSIX package:

# Download
curl -LO https://github.com/avwohl/cpmemu/releases/latest/download/cpmemu.msix

# Install (double-click the file, or use PowerShell)
Add-AppPackage cpmemu.msix

After installation, cpmemu is available from any command prompt or PowerShell window.

Linux (Debian/Ubuntu)

curl -LO https://github.com/avwohl/cpmemu/releases/latest/download/cpmemu_amd64.deb
sudo dpkg -i cpmemu_amd64.deb

For ARM64 systems, use cpmemu_arm64.deb instead.

Linux (RHEL/Fedora)

curl -LO https://github.com/avwohl/cpmemu/releases/latest/download/cpmemu.x86_64.rpm
sudo rpm -i cpmemu.x86_64.rpm

For ARM64 systems, use cpmemu.aarch64.rpm instead.

From Source

See docs/BUILDING.md for detailed build instructions.

Quick start (Linux):

git clone https://github.com/avwohl/cpmemu.git
cd cpmemu/src
make
sudo cp cpmemu /usr/local/bin/

Quick start (Windows with Visual Studio):

git clone https://github.com/avwohl/cpmemu.git
cd cpmemu\src
do_build.bat

Usage

cpmemu [options] <program.com> [args...]

Options

| Option | Description | |--------|-------------| | --8080 | Run in 8080 mode (default) | | --z80 | Run in Z80 mode with full instruction set | | --progress[=N] | Report progress every N million instructions (default: disabled; 100 if flag used without N) |

Examples

Windows:

cpmemu program.com
cpmemu --z80 program.com
cpmemu mbasic.com myprogram.bas

Linux:

cpmemu program.com
cpmemu --z80 program.com
cpmemu mbasic.com myprogram.bas

Running Microsoft BASIC

> cpmemu mbasic.com
BASIC-80 Rev. 5.21
[CP/M Version]
Ok
10 PRINT "Hello, CP/M!"
20 END
RUN
Hello, CP/M!
Ok
SYSTEM

Environment Variables

| Variable | Description | |----------|-------------| | CPM_PROGRESS=N | Progress reporting every N million instructions | | CPM_PRINTER | File path for LIST device (printer) output | | CPM_AUX_IN | File path for Reader device input | | CPM_AUX_OUT | File path for Punch device output | | CPM_BIOS_DISK | Control BIOS disk behavior: ok, fail, or error | | CPM_DEBUG_BDOS | Debug specific BDOS functions (comma-separated numbers) | | CPM_DEBUG_BIOS | Debug specific BIOS offsets (comma-separated numbers) |

Configuration Files

For complex setups, use a .cfg file:

# Program to run
program = /path/to/program.com

# File mode settings
default_mode = auto      # auto, text, or binary
eol_convert = true       # Convert Unix \n <-> CP/M \r\n

# Device redirection
printer = /tmp/printer.txt
aux_input = /tmp/input.txt
aux_output = /tmp/output.txt

# File mappings (supports environment variables)
# *.BAS = ${HOME}/basic/*.bas text
# DATA.DAT = /path/to/data.dat binary

Run with: ./src/cpmemu config.cfg

Supported CP/M Functions

BDOS Functions

| # | Function | Status | |---|----------|--------| | 0 | System Reset | Supported | | 1 | Console Input | Supported | | 2 | Console Output | Supported | | 3-5 | Auxiliary/List I/O | Supported | | 6 | Direct Console I/O | Supported | | 7-8 | Get/Set IOBYTE | Supported | | 9 | Print String | Supported | | 10 | Read Console Buffer | Stub (returns 0) | | 11 | Console Status | Supported | | 12 | Get Version | Supported | | 13-14 | Reset/Select Disk | Supported | | 15-16 | Open/Close File | Supported | | 17-18 | Search First/Next | Supported | | 19 | Delete File | Supported | | 20-21 | Read/Write Sequential | Supported | | 22 | Make File | Supported | | 23 | Rename File | Supported | | 24-32 | Disk Operations | Supported | | 33-34 | Read/Write Random | Supported | | 35 | Compute File Size | Supported | | 36 | Set Random Record | Supported | | 37 | Reset Drive | Supported | | 38 | Access Free Space | Stub (returns success) | | 39 | Free Space | Stub (no-op) | | 40 | Write Random Zero Fill | Supported |

BIOS Functions

Console I/O: CONST, CONIN, CONOUT (implemented)
Device I/O: LIST, PUNCH, READER, LISTST (implemented)
Disk Operations: Stubs only (return success/fail per CPM_BIOS_DISK setting)

CP/M Memory Layout

0x0000-0x0004  Bootstrap vector to WBOOT
0x0003         IOBYTE (device control)
0x0004         Current drive/user
0x0005         Entry point to BDOS
0x005C-0x006B  Default FCBs
0x0080-0x00FF  Default DMA buffer (command line)
0x0100-0xFBFF  TPA (Transient Program Area)
0xFC00         CCP (Console Command Processor)
0xFD00         BDOS jump table
0xFE00         BIOS jump table

Testing

cd src/
make test                                    # Run quick tests
timeout 180 ./cpmemu ../tests/zexdoc.com     # Z80 documented instruction test
timeout 180 ./cpmemu ../tests/zexall.com     # Z80 all instructions test

The tests/ directory contains various test programs including:

Console and flag tests
Zexdoc/Zexall Z80 instruction verification
8080-specific tests in tests/8080/

Project Structure

cpmemu/
├── src/
│   ├── cpmemu.cc          # Main emulator and CP/M system
│   ├── qkz80.h/cc         # Z80/8080 CPU core
│   ├── qkz80_reg_set.*    # Register set implementation
│   ├── qkz80_mem.*        # Memory management
│   ├── os/
│   │   ├── platform.h     # Platform abstraction interface
│   │   ├── linux/         # Linux/POSIX implementation
│   │   └── windows/       # Windows implementation
│   ├── makefile           # Linux build
│   ├── Makefile.win       # Windows/MinGW build
│   ├── CMakeLists.txt     # CMake cross-platform build
│   └── do_build.bat       # Windows/MSVC build script
├── packaging/
│   └── windows/           # MSIX packaging for Windows Store
├── tests/                 # Test programs (.com and .asm)
├── com/                   # Sample CP/M programs (mbasic.com)
├── examples/              # Configuration file examples
└── docs/                  # Documentation and references

Related Projects

80un - Unpacker for CP/M compression and archive formats (LBR, ARC, squeeze, crunch, CrLZH)
cpmdroid - Z80/CP/M emulator for Android with RomWBW HBIOS compatibility and VT100 terminal
ioscpm - Z80/CP/M emulator for iOS and macOS with RomWBW HBIOS compatibility
learn-ada-z80 - Ada programming examples for the uada80 compiler targeting Z80/CP/M
mbasic - Modern MBASIC 5.21 Interpreter & Compilers
mbasic2025 - MBASIC 5.21 source code reconstruction - byte-for-byte match with original binary
mbasicc - C++ implementation of MBASIC 5.21
mbasicc_web - WebAssembly MBASIC 5.21
mpm2 - MP/M II multi-user CP/M emulator with SSH terminal access and SFTP file transfer
romwbw_emu - Hardware-level Z80 emulator for RomWBW with 512KB ROM + 512KB RAM banking and HBIOS support
scelbal - SCELBAL BASIC interpreter - 8008 to 8080 translation
uada80 - Ada compiler targeting Z80 processor and CP/M 2.2 operating system
uc80 - ANSI C compiler targeting Z80 processor and CP/M 2.2 operating system
ucow - Unix/Linux Cowgol to Z80 compiler
um80_and_friends - Microsoft MACRO-80 compatible toolchain for Linux: assembler, linker, librarian, disassembler
upeepz80 - Universal peephole optimizer for Z80 compilers
uplm80 - PL/M-80 compiler targeting Intel 8080 and Zilog Z80 assembly language
z80cpmw - Z80 CP/M emulator for Windows (RomWBW)

Cpmemu

Install / Use

README