The Dragon 32/64 Computers

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Introduction

The Dragon is an 8-bit personal computer based upon the Motorola MC6809E microprocessor. Made in Wales by Dragon Data Ltd., two variants were sold in the UK: the Dragon 32 (32K RAM) and the Dragon 64 (64K RAM, serial port, other very minor differences). The on-board ROM contains a version of Microsoft Extended Colour BASIC, but more advanced operating systems like NitrOS-9 (a modern redevelopment of OS-9) and FLEX are available.

An NTSC version of the Dragon 64 was released in the USA as the Tano Dragon. Eurohard later repackaged the Dragon 64 in Spain as the Dragon 200, and also produced a localised version called the Dragon 200-E.

David Linsley has written a comprehensive history, available here (PDF).

Software

Available for download from this site:

XRoar

A free, cross-platform emulator of Dragon 32/64, Tano Dragon and Tandy Colour Computer 1/2.

6809 GDB

Modifications to GDB to support a 6809 remote target.

dzip

Simple compression tool. Compression rates are reasonable, decompression is very fast, and the 6809 decompress loop is only 39 bytes long. Used in the loaders for the Nyan Cat demo.

For better compression, but much slower & larger decompress routines, have a look at Exomizer 2.

asm6809

A 6800/6801/6803/6809/6309 macro cross assembler written in Perl. Quite good at generating efficient output. ISAs other than 6809 and 6309 are not very well tested.

This prerelease of a work in progress C port only handles 6809. The syntax it handles is almost the same; as before, if you want proper Motorola syntax, check out LWTOOLS instead. The latest prerelease uses functions from Gnulib instead of GLib, and builds more readily for Windows using MinGW.

6809dasm.pl

A 6809 disassembler written in Perl. The aim is to always produce code that can be reassembled by "asm6809". Now with 6309 support and ability to annotate output with comments.

Demos

A collection of demo or work-in-progress (or possibly destined to remain proof-of-concept) Dragon software.

cas2wav

Convert a Dragon/Tandy CoCo CAS file to WAV. Options control sample rate, number of channels, etc. No intelligent parsing of CAS file performed, just bits to waves.

PD Dragon 1 & 2

The two Dragonfire public domain disks. There are a couple of little adventure games in there (probably by Robin Hemmings). Most interesting to me was "1770.BAS" (by M. Edwards) which allowed you to read BBC Micro disks.

Code snippets

keyboard.s
Standalone keyboard scanning routine.
rnd.s
Simple 16-bit PRNG - almost certainly originally from Dragon User.
crc16.s
6809 implementation of CRC-16-CCITT.

Documentation

From other sources:

Note: The 6309 is a version of the 6809 created by Hitachi, and includes more instructions, extra registers and a native, faster, execution mode.

Other sites about the Dragon:

And less directly Dragon-related:

Images

 

Updated 3 Apr 2014