Microcomputer History

As someone who was "there" during the early development of the MicroComputer industry, I have a keen interest in documenting and preserving this period of rapid growth in our technological development with special attention to Canadian accomplishments.

I maintain a collection of over 200 classic systems as well as documentation, software and related material. My activities include ongoing maintenance, repair, demonstrations, and providing knowlege and resources to museums, collectors and other interested parties.

I am also involved in the preservation and archival of documentation and system software relating to classic computers, and in the conversion of these into modern electronic forms for long term archival.

I maintain a web site devoted to making this collection available to interested persons. This takes the form of detailed "inside and out" photographs, documentation, simulations and other resources relating to the systems and the early microcomputer industry in general.

You can view my collection at: http://www.classiccmp.org/dunfield/

Software Preservation Tools

Here are some of the tools that I have developed to assist in the preservation of original system software for classic computer systems:


ImageDisk is a program I created which allows you to read, archive and recreate virtually ANY format diskette that can be accessed with the NEC 765 compatible diskette controller in an IBM PC type machine. ImageDisk performs an analysis of each track, and records detailed information about the disk format in the image file along with the sector data. ImageDisk has manyoptions, and can handle a very wide variety of diskette formats.

A companion program IMDU (ImageDisk Utility) allows you to extract a detailed track by track report on the format and content of a disk image, as well as to merge multiple partial images into a single complete archive. IMDU can also convert disk image files into a raw binary dump of the disk content. A second utility BIN2IMD allows you to construct .IMD images from raw binary sector data, allowing you to create images - and physical disks from other sources. A viewer (IMDV) makes it easy to examine the content of a disk image, edit sectors, extract printable strings, search for specific strings etc.

My work with ImageDisk included interfacing 8" diskette drives to PCs so that I can archive and restore software on this media format.

CP/M Transfer

CPT is a system I created to archive/restore CP/M disk images via a serial connection between a PC and the classic computer running CP/M. It is useful for archiving hard sectored and other format for various CP/M based systems which cannot be preserved with ImageDisk.

NorthStar Transfer

NST is a system I created to archive/restore Single and Double density NorthStar hard-sectored formats via a serial connection to a system with the NorthStar controller. This is the only means I am aware of to preserve NorthStar disks.

A companion program NSI (NorthStar Image) allows access to the individual files in a NorthStar DOS format disk. NST/NSI images are also directly usable by my NorthStar Horizon and Altair 8800 simulators.

RDOS Transfer

RDOS Transfer is a system I created to archive and restore diskettes for the Cromemco series of microcomputers. Transfer is accomplished by the PC entering commands into the resident Cromemco RDOS monitor program at high speed. This is the only way to bootstrap some Cromemco systems.

H8 Translate/Transfer

H8T is a program I created to translate between Heathkit H8 tape images, PC binary files, and PC ascii-hex download files. It can also transfer any of these formats to or from the H8 computer system via a serial connection and the H8 PAM8 monitor rom.


This section describes a number of simulations that I have developed for some of the classic computer systems in my collection.

Altair 8800

The Altair is considered by many to be the first personal computer. This was my first computer of substantial capability. Included in the simulation are the 8080 CPU, Memory, console, North-Star disk controller and Real time clock systems, as well as the Altair front panel, a ADM3A terminal, and comprehensive debugger.

The system boots NorthStar DOS and my own DMF operating system.

With this simulator, you can boot "my" 1975 Altair 8800, run the first operating system I ever created, and use many of earliest tools.


The MIL MOD-8 is one of the earliest Canadian microprocessor based systems. Included in the simulation are the 8008 CPU, ROM/RAM, bit-bash TTY interface, 1702 Eprom programmer and parallel I/O ports.

This system boots up into the actual MOD8 monitor program, and allows you to experience using an early Canadian system from 1974.

Heathkit H8

The H8 is one of the earliest microcomputer systems to use a CPU/software based front panel. Included in the simulation are the 8080 CPU, memory, H8 console and I/O devices as well as the H17 disk system, an H9 terminal, and a comprehensive debugger.

The system can bootstrap from H8 tape images, and the Heathkit HDOS system from virtual diskette.

With this simulator, you can experience using a 1977 H8 system, running games from tape, or HDOS from disk.

NorthStar Horizon

The Horizon is one of the earliest "turnkey" systems. Included in the simulation are the Z80 CPU, memory, NorthStar mainboard devices and console, as well as the NorthStar single and double density disk systems, and a TeleVideo terminal. A comprehensive debugger is also provided.

The system boots CP/M, NorthStar DOS and my own DMF operating system.

With this simulator you can experience using a 1976 S-100 CP/M or NorthStar DOS based business system.

Dunfield 6809/CUBIX

The Dunfield 6809 is a completely self-designed MicroComputer system. Not only is the main logic all hand assembled (wire-wrap) logic, the system software (quite powerful for the time) is also all designed by yours truly. The simulation includes the 6809 CPU, Memory, video display, keyboard, serial I/O, and disk subsystems, as well as a comprehensive debugger. The system boots my own CUBIX operating system.

With this simulator you can experience using a totally home-built computer system from the early 1980s.

Contact Information

Copyright 2012-2019 Dave Dunfield.