I was born in 1972, and ever since I first came into contact with a computer as a child, I have been fascinated by the possibility of controlling, moving or regulating something simply by entering a few characters. Unfortunately, my parents considered all of it the work of the devil, so it took a few years before I could afford my first home computer. While other children were swapping C64 games in the schoolyard, I was still staring at a blank screen—there simply was no computer connected to the tube. :) I spent every free minute in department stores or visiting school friends who owned a home computer. My first computer was a Commodore C16, sold by Aldi for DM 149 at the end of 1985. A Nascom was therefore completely out of reach at the time. Once I was old enough to work during the school holidays, I bought everything I could find on the second-hand market: a C64, C128, Amiga 500, Amiga 2000 and an Atari ST. I simply had too little money to take sides in the platform wars. When alando.de appeared in the mid-1990s, I bought all the old computers I had previously only heard about. Today I own a sizeable collection of vintage home computers. It was not until 2010 that I happened upon an unpopulated Nascom 2 circuit board with its manuals on eBay. I reconstructed it over the following two years and came to appreciate this quirky computer rather late in life.
When the first FPGAs appeared, my desire to learn how to program these devices began to grow. It was the same idea that had fascinated me before: I enter something and the hardware does exactly what I want. This time, however, I could program the entire hardware without heating up a soldering iron. Money was no longer the obstacle, but time was. I repeatedly made it as far as clock dividers and chains of blinking LEDs, but never progressed beyond that point.
At the beginning of 2026, I finally took the plunge, made the time and immersed myself in FPGA development using VHDL. I had already owned the MEGA65 for a while, and it was immediately clear that this would become my platform. I started with an existing Z80 processor core—the T80 from OpenCores—and attached everything else it needed: some RAM and ROM, reset circuitry and timing. With that, I had recreated my Z80EMUF. I was surprised by how quickly and easily it came together. So I continued, step after step, and recreated the Nascom 2 together with many of its extensions. Sometimes I can hardly believe how far the project has come. I hope I can sustain this motivation for a long time and recreate several more interesting niche computers. The next one will probably be the BIT90, another little-known machine that is consequently not emulated very often.
The Nascom 2 as a starting point
The Nascom 2 is particularly well suited to this approach. Its architecture is manageable, close to the hardware and still open enough to support very different kinds of software. NAS-SYS, BASIC, floppy operation, CP/M and expansion boards demonstrate how a comparatively simple computer developed into a complete workstation.
The MEGA65 implementation combines this historic structure with an accessible FPGA platform. The behaviour of the original machine remains the reference point. Modern features are intended to make practical operation easier without obscuring the character of the system.
Technical principles
- Historic behaviour is recreated as accurately as reasonably possible.
- Differences and extensions are documented clearly.
- Modern features remain optional and controllable wherever possible.
- Memory maps, interfaces and operation should be openly understandable.
- The core is tested on real hardware and improved incrementally.
- Documentation and the working system evolve together.
Beyond a single core
The Nascom 2 is the first system to receive comprehensive documentation, but it is not intended to be the last. In the long term, I plan to study, implement and present further classic computers in FPGA. The goal is not to produce as many systems as possible in a short time, but to explore technically interesting machines and support them with reliable documentation.
Under the name emuversum.de, these projects may eventually share a common home: a collection of classic computers, their architectures, their software and their modern FPGA implementations.
The current path
This project grows in traceable steps. Features are implemented, tested on the MEGA65 and then documented. Unfinished areas are identified as such. The result should become a technical reference that helps both with using the core and with understanding the original computer.
Contact and contributions
Bug reports, technical information and additions are always welcome. This applies especially to:
- reproducible bugs in the core or documentation
- Nascom software, disk images or programs not yet covered here
- information about historic hardware, expansion boards and custom modifications
- corrections, additional sources and other technical comments
- questions about installation, operation or development
Please write to mega65@nascom2.de. When reporting a bug, a short description, the core version, the MEGA65 hardware revision and precise steps for reproducing the problem are particularly helpful.