Porting a game from BBC Micro to Dragon 32

Nice in-depth blog here about porting Dunjunz, a BBC Micro version of Gauntlet, to the 6809-based Dragon machines.


Dunjunz (by Julian Avis for Bug Byte) is basically a home computer) version of Gauntlet […] each player gets their own window. This greatly enhances gameplay in my view: everyone can go off and do their own thing without being constrained by the position of the others.

Nothing like this existed for the Dragon, so obviously I had to write my own version. I spent a lot of time on this (ah, school days, with so much time free to work on things by the simple expedient of not doing your homework): designing graphics, making levels, coding it all up in assembly language then finally losing the disk. Such is life.

In 2006, James McKay released Glove, a Gauntlet clone for the Dragon and Tandy CoCo. It’s pretty excellent. Full screen scrolling, lots of monsters, all the usual Gauntlet stuff. You could even buy it on tape. And you should!

But it ain’t Dunjunz.

So a few years ago (and to really put this into context, that’s another eight years later ), I started tinkering again. After all, I’ve got a pretty good emulator. I’ve got a serviceable cross-assembler. And in theory I can even stop working when I get home so that I have the time.

Mostly what I did was prove to myself I could have a map and have things wandering around that map. This also forced a few decisions about the constraints a new approach would have to work within.

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Great read!
Supporting all the various models of Dragon and CoCo computers, including various RAM sizes, color systems (PAL and NTSC artifact colors via but shifting) and input methods (keyboard, digital joysticks, analog joysticks with and w/o self-center) adds a dimension rarely found on other home computer platforms. Quite impressive to manage this in a single piece of code.

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A complementary video on the Dragon 32 added recently by YouTuber RetroManCave:

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