CP/M Plus "Continuous Integration" build environment

This repository contains a Docker environment for building CP/M Plus from source.

Introduction

CP/M Plus (aka CP/M 3) was an 8-bit operating system released in 1983 by Digital Research Inc, for 8080 / Z80 based microcomputers. CP/M Plus, and the earlier CP/M 2.2, were widely ported to many microcomputers during the 1980s.

Much later, in the late 1990s or early 2000s various source code to Digital Research microcomputer products was released, under various licenses from the then corporate owners of Digital Research assets. This included source code for (most of) CP/M Plus.

The current license for the CP/M Plus source code is from an email to the maintainers of The Unofficial CP/M Web Site, and says in the key part:

Let this paragraph represent a right to use, distribute, modify, enhance, and otherwise make available in a nonexclusive manner CP/M and its derivatives. This right comes from the company, DRDOS, Inc.'s purchase of Digital Research, the company and all assets, dating back to the mid-1990's. DRDOS, Inc. and I, Bryan Sparks, President of DRDOS, Inc. as its representative, is the owner of CP/M and the successor in interest of Digital Research assets.

(where DRDOS was originally the Digital Research version of DOS, derived from CP/M-86 plus some comptability layers).

Building CP/M Plus

John Elliot did all the work to determine how to build CP/M Plus under Linux, including writing a couple of emulators to run the build tools under Linux:

• ZXCC which runs CP/M binaries under Linux, with I/O redirection to files

• Thames which runs Intel ISIS-II binaries under Linux, with I/O redirection to files

The build process is bootstrapped from the Intel ISIS II environment ("Intel System Implementation Supervisor"), where the PL/M (Programming Language for Microcomputers) compiler (plm80) and Intel assembler (asm80) were run to build the source, with later steps being done in a CP/M environment.

This repository just automates installing ZXCC, Thames, the PLM80/ASM80 compiler/assembler, and setting up the build environment. Then runs the Makefile provided by John Elliot, and copies the generated output files.

Usage

Install Docker, and make sure it is usable by the user you are running these tools.

Optionally run:

./download-tools

first to download from the Internet the source and tools required (this is a one time download step).

Optionally run:

docker build -t cpm-ci .

to pre-build the Docker image with the emulator/compiler tools ready to use.

Then run:

./build-cpm

in the top level directory to build CP/M from the cpm-source/cpm3src_unix.zip file, and place the generated files in the output/ directory. (It will automatically run the ./download-tools step, and the docker build -t cpm-ci . step, if it detects those have not been done.)

See also

The z80pack emulator includes a guide to building CP/M Plus under CP/M Plus and CP/M 2.2 (needed for the ISIS-II emulator for CP/M, which does not run under CP/M Plus). It is not quite as automated a build, but runs on an emulation of "period correct" hardware, rather than being a full Linux-cross-compile build through emulators like here.

Mark Ogden has enhanced the Thames ISIS emulator so that it can run more programs. And used it in reverse engineering and rebuilding many Intel 8080 / ISIS programs. He has also ported several of the early Intel tools to C/C++, so they can be built to run natively on modern systems.