The Dragon 32/64 Computers

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• Introduction
• Software
• Documentation
• Links
• Images

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 (basic version, 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, and Eurohard repackaged it in Spain as the Dragon 200.

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.

• XRoar home page.

dzip

Simple compression tool with a fast 6809 decompress routine. The compress tool is pretty slow, but the 6809 decompress loop is only 39 bytes long and quite fast. Used in the loaders for the Nyan Cat demo.

• dzip.tar.gz source tarball.

asm6809.pl

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

• asm6809.pl Perl script v1.10.
• asm6809.pl old Perl script v0.11.
• Usage guide.
• Git repository.

6809dasm.pl

A 6809 disassembler written in Perl. The aim is to always produce code that can be reassembled by "a09" (or perhaps more reasonably, by "asm6809.pl"). Now with 6309 support.

• 6809dasm.pl Perl script.
• 6809dasm.pl-0.1 old Perl script.
• Usage guide.

Demos

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

• Dragon Demos.

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.

• cas2wav-0.6.tar.gz source tarball.

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.

• Archive containing both virtual disks: pd_dragon.zip.

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

• Hardware details - how the Dragon is put together.

From other sources:

• 6809 Pinout and instruction set (local copy of a document by Jonathan Bowen).
• Technical information on the 6309 (local copy of a document by Chet Simpson and Alan DeKok).
• Fitting a 6309 (local copy of a document by Chris Burke).

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

Links

Other sites about the Dragon:

• The Dragon Archive Online. Including documentation, discussion forums and software downloads.
• Dragon Data Archive: lots of historical information about the company and pictures of hardware, including the Dragon Alpha (Professional) and Beta (128).
• Jon Bird has some good stuff on OS-9 and interesting hardware modifications.
• Paul Burgin's Dragon page, including:
  • Description Of The Motorola 6809 Instruction Set.
  • Description of the Dragon Keyboard And Video Hardware.
• Graham Kinns's Dragon page, with lots of useful information files.
• Archived Dragon Miscellany, collects the old, probably useless, items from this page.

And less directly Dragon-related:

• 6809 Emulation Page - lots of information on the CPU.
• CoCoList is a mailing list "for enthusiasts of the Color Computer in all its forms, its clones, and its software".
• CoCo Games Workshop Forum. A relative newcomer that has already fostered some excellent technical discussion.
• Tandy Color Computer Forums. Discussion forum with many subsections.
• L. Curtis Boyle's CoCo 1/2/3 web pages. Containing a fairly comprehensive list of CoCo games, many of which were also released for the Dragon.
• David Roper has worked on a Lemmings clone for the CoCo 3, blogging about it as he goes.

Images

• 
  Dragon 64 + Disk Drives
• 
  6809 CPU
• 
  6309 CPU

Updated 31 Jan 2013