The Compusense DragonPlus
Back in late 1985, a new board was released by a company called Compusense. This company, run by Tad Opyrchal, had already published much successful software as well as versions of OS9 and Flex for the Dragon. This board was truly the ultimate board back in 1985/6, adding a new high resolution 80 x 24 character text screen and an additional 64K virtual RAM to a Dragon 64 (or upgraded Dragon 32).
Somehow I completely overlooked the board back in the 80s, but having studied the details of it in early 2018, decided I wanted to have a go at recreating it. Bearing in mind that I’d started, and then stopped trying to produce a DragonDOS cartridge PCB, and that the DragonPlus board is perhaps ten times as complex, this was no mean feat.
Suffice to say that over one year later, I reached the point where I was confident that my fifth or sixth revision of the reproduced board was suitable for sale. Several of those boards have now been sold in built, kit and 32/64 formats, and their continued availability has been the driver for this new website.
I Didn’t Manage It Alone
Various people have helped me along the DragonPlus journey – and I have to say that without this support from the Dragon community, it just wouldn’t have happened. When reading the following, you must understand that I had never seen an original DragonPlus board at the outset, and did not do so until several months after I’d first produced boards.
Special thanks are due to the following people:
Phill Harvey-Smith – without a doubt, the most help has come from Phill. From the very first encouragement, to the excellent PCB traces which he’d done several years earlier. He looked at early versions of my boards, building them his end and fault-finding where I’d frankly come to a complete dead-end. He also provided me with suitable floppy drives and test routines that enabled diagnosis of the DragonPlus board without needing to load off-the-shelf software (which had it’s own complexities).
Robert Schofield – Rob swiftly changed my way of thinking with the initial development of these boards. I’d planned to use Eagle – even though it had limitations caused by the modern license terms. I naively thought I’d design the board up to a certain size, and then pay a small license fee when it went over those dimensions. Rob told me about KiCad. It took a while to learn, but I’ve never looked back.
Tony Jewell – as well as being somewhat of a bad influence in the realm of temptation when it comes to encouraging me to develop boards (like the later Dragon 200E daughterboards), Tony works at the Cambridge Centre for Computer History, and has great contacts in the retro computing world. Tony not only has taken images of his original DragonPlus boards, as well as measured header pin lengths etc, but he also put me in touch with Tad Opyrchal, the Managing Director of Compusense back in the 80s and 90s.
Tad Opyrchal – very early on in the development of this project, I got in touch with Tad, via Tony. Having explained to Tad what I wanted to do, he was full of support for the project, and said he had no objections whatsoever to me recreating these boards – as long as it was obvious that they were reproductions. He was happy for me to use the DragonPlus name for them.
Bas Gialopsos – Having seen me go through some rather frantic periods of failing DragonPlus boards, Bas offered me some help to validate the robustness of these boards. Essentially I was pretty sure that they worked, but I was having so many environmental issues with successfully proving that. Bas built one of the boards, and tested it thoroughly, giving me the confidence to commence production finally of these boards, in both built and kit form.
Rob Owen – Rob very kindly took me some excellent close-up images of his original DragonPlus board. They were a huge help in understanding the exact components that were used for the boards, as well as some of the finer design points.
Tim Gilberts – Tim bought one of my first kits, and he planned to fit it into a Dragon 32. He found a fair few issues which I’d not encountered in my own D32 installation, down to the different motherboard configurations. It’s thanks to Tim’s input that various things like header pins and the 26-way IDC socket arrangement have been refined.
If I’ve forgotten to add anyone to this list, please do let me know – they deserve recognition. I’d also like to generally thank the entire Dragon retro community, who have been patiently suffering my various DragonPlus rants over a year or so, and who have showed their support for the product once it finally became available.
If you’d like to read even more about the development of the DragonPlus 2019 boards, please download the following PDF.