RomWBW Introduction
Version 3.6
Wayne Warthen (wwarthen@gmail.com)
20 Mar 2026

Overview

RomWBW software provides a complete, commercial quality implementation of CP/M (and work-alike) operating systems and applications for modern Z80/180/280 retro-computing hardware systems.

A wide variety of platforms are supported including those produced by these developer communities:

A complete list of the currently supported platforms is found in RomWBW Hardware .

Description

Primary Features

By design, RomWBW isolates all of the hardware specific functions in the ROM chip itself. The ROM provides a hardware abstraction layer such that all of the operating systems and applications on a disk will run on any RomWBW-based system. To put it simply, you can take a disk (or CF/SD/USB Card) and move it between systems transparently.

Supported hardware features of RomWBW include:

Z80 Family CPUs including Z80, Z180, and Z280
Banked memory services for several banking designs
Disk drivers for RAM, ROM, Floppy, IDE ATA/ATAPI, CF, SD, USB, Zip, Iomega
Serial drivers including UART (16550-like), ASCI, ACIA, SIO
Video drivers including TMS9918, SY6545, MOS8563, HD6445, Xosera
Keyboard (PS/2) drivers via VT8242 or PPI interfaces
Real time clock drivers including DS1302, BQ4845
Support for CP/NET networking using Wiznet, MT011 or Serial
Built-in VT-100 terminal emulation support

A dynamic disk drive letter assignment mechanism allows mapping operating system drive letters to any available disk media. Additionally, mass storage devices (IDE Disk, CF Card, SD Card, etc.) support the use of multiple slices (up to 256 per device). Each slice contains a complete CP/M filesystem and can be mapped independently to any drive letter. This overcomes the inherent size limitations in legacy OSes and allows up to 2GB of addressable storage on a single device, with up to 128MB accessible at any one time.

Included Software

Multiple disk images are provided in the distribution. Most disk images contain a complete, bootable, ready-to-run implementation of a specific operating system. A “combo” disk image contains multiple slices, each with a full operating system implementation. If you use this disk image, you can easily pick whichever operating system you want to boot without changing media.

Some of the included software:

Operating Systems (CP/M 2.2, ZSDOS, NZ-COM, CP/M 3, ZPM3, Z3PLUS, QPM )
Support for other operating systems, p-System, FreeRTOS, and FUZIX.
Programming Tools (Z80ASM, Turbo Pascal, Forth, Cowgol)
C Compiler’s including Aztec-C, and HI-TECH C
Microsoft Basic Compiler, Microsoft Fortran, and Microsoft COBOL
Some games such as Colossal Cave, Zork, etc
Wordstar Word processing software

Some of the provided software can be launched directly from the ROM firmware itself:

System Monitor
Operating Systems (CP/M 2.2, ZSDOS)
ROM BASIC (Nascom BASIC and Tasty BASIC)
ROM Forth

A tool is provided that allows you to access a FAT-12/16/32 filesystem. The FAT filesystem may be coresident on the same disk media as RomWBW slices or on stand-alone media. This makes exchanging files with modern OSes such as Windows, MacOS, and Linux very easy.

ROM Distribution

The RomWBW Repository (https://github.com/wwarthen/RomWBW) on GitHub is the official distribution location for all project source and documentation.

RomWBW is distributed as both source code and pre-built ROM and disk images.

The pre-built ROM images distributed with RomWBW are based on the default system configurations as determined by the hardware provider/designer. The pre-built ROM firmware images are generally suitable for most users.

The fully-built distribution releases are available on the RomWBW Releases Page (https://github.com/wwarthen/RomWBW/releases) of the repository.

On this page, you will normally see a Development Snapshot as well as recent stable releases. Unless you have a specific reason, I suggest you stick to the most recent stable release.

The asset named RomWBW-vX.X.X-Package.zip includes all pre-built ROM and Disk images as well as full source code. The other assets contain only source code and do not have the pre-built ROM or disk images.

Distribution Directory Layout

The RomWBW distribution is a compressed zip archive file organized in a set of directories. Each of these directories has its own ReadMe.txt file describing the contents in detail. In summary, these directories are:

| Directory | Description | |----|----| | Binary | The final output files of the build process are placed here. Most importantly, the ROM images with the file names ending in “.rom” and disk images ending in .img. | | Doc | Contains various detailed documentation, both RomWBW specifically as well as the operating systems and applications. | | Source | Contains the source code files used to build the software and ROM images. | | Tools | Contains the programs that are used by the build process or that may be useful in setting up your system. |

Building from Source

It is also very easy to modify and build custom ROM images that fully tailor the firmware to your specific preferences. All tools required to build custom ROM firmware under Windows are included – no need to install assemblers, etc. The firmware can also be built using Linux or MacOS after confirming a few standard tools have been installed.

Installation & Operation

In general, installation of RomWBW on your platform is very simple. You just need to program your ROM with the correct ROM image from the RomWBW distribution. Subsequently, you can write disk images on your disk drives (IDE disk, CF Card, SD Card, etc.) which then provides even more functionality.

Complete instructions for installation and operation of RomWBW are found in the RomWBW User Guide. It is also a good idea to review the Release Notes for helpful release-specific information.

Documentation

There are several documents that form the core of the RomWBW documentation:

RomWBW User Guide is the main user guide for RomWBW, it covers the major topics of how to install, manage and use RomWBW, and includes additional guidance to the use of some of the operating systems supported by RomWBW
RomWBW Hardware contains a description of all the hardware platforms, and devices supported by RomWBW.
RomWBW Applications is a reference for the ROM-hosted and OS-hosted applications created or customized to enhance the operation of RomWBW.
RomWBW Disk Catalog is a reference for the contents of the disk images provided with RomWBW, with a description of many of the files on each image
RomWBW System Guide discusses much of the internal design and construction of RomWBW. It includes a reference for the RomWBW HBIOS API functions.

An online HTML version of this documentation is hosted at https://wwarthen.github.io/RomWBW.

Each of the operating systems and ROM applications included with RomWBW are sophisticated tools in their own right. It is not reasonable to fully document their usage. However, you will find complete manuals in PDF format in the Doc directory of the distribution. The intention of this documentation is to describe the operation of RomWBW and the ways in which it enhances the operation of the included applications and operating systems.

Since RomWBW is purely a software product for many different platforms, the documentation does not cover hardware construction, configuration, or troubleshooting – please see your hardware provider for this information.

Support

Getting Assistance

The best way to get assistance with RomWBW or any aspect of the RetroBrew Computers projects is via one of the community forums:

Submission of issues and bugs are welcome at the RomWBW GitHub Repository.

Also feel free to email Wayne Warthen at wwarthen@gmail.com. I am happy to provide support adapting RomWBW to new or modified systems

Contributions

All source code and distributions are maintained on GitHub. Contributions of all kinds to RomWBW are very welcome.

Acknowledgments

I want to acknowledge that a great deal of the code and inspiration for RomWBW has been provided by or derived from the work of o

RomWBW

Install / Use

README