Alan DeKok's 6809 Page

What exactly is the Motorola 6809?

Well, now we know. Tim Lindner has typed in a series of articles about the 6809 from a January 1979 Byte magazine, and has made the first installment available in electronic format. There are no pictures in the document, however, as he re-typed them from old photocopies, and the pictures were too faded to scan properly.

The document The 6809 Part 1 & 2 is available in pdf, and in postscript format (postscript has part 1, only). One of the 6809's designers and authors of the article, Terry Ritter, describes his work on the 6809 in his resume.

Undocument op-codes of the 6809 are few. Note that because the 6809's instructions are bit decoded, '$00' is the same as '$01'. So the lower order bits of an instruction don't affect it's decoding. For example, NEG (direct) is really 0b0000000*, where the '*' means '0 OR 1'.

There's also something called the Hitachi 6309, which is a CMOS version with extra registers, instructions, and a '6309 native' execution mode. Although rated at 3MHz, it will do 5Mhz with proper cooling. A full 6309 technical reference is available for public perusal. (HTML version) A 6809 pinout is available from the Giant Internet IC Masturbator.

Sadly, rumor has it that Hitachi has discontinued the 6309, despite the fact that 6309 modifications to 6809 software results in it doing pretty much double the work at the same clock speed.

I've found a 6809 gcc compiler. Well, it's not really gcc, but it's free, and includes an assembler. I've got a 6809 disassembler, too.

gcc problems:

Happily, there's an updated version. See: this link for details.

A much better organized site than this...

The 6809 Emulation Page has a lot of interesting 6809 links, with assemblers, emulators, instruction information, etc. Very cool.

Cross assemblers and Disassemblers

Much of this was gleaned from comp.sys.m6809, and edited slightly.
There is a M6809/H6309 cross assembler released for Amiga/AmigaOS and IBM-PC(-compatible)/MS-DOS hosts.

   Copyright 1990-1993, Frank A. Vorstenbosch, Kingswood Software
   P.O. Box 85800  2508CM  The Hague  Netherlands
I have uploaded to simtel updated versions of the ASxx assembler packages. In this version, full support for macros has been added. Watch out for it, it should come on-line in the first week of march.
AS02 [1.11] - Assembler for M6800/6801/6802/6803 microprocessor.
AS05 [1.11] - Assembler for M6805 microprocessor.
AS09 [1.11] - Assembler for M6809/H6309 microprocessor.
AS48 [1.11] - Assembler for i8048/49/50 microprocessor.
AS65 [1.11] - Assembler for R6502/65SC02 microprocessor.
AS80 [1.11] - Assembler for i8080-Z180 microprocessor.
READDBG - Sample code to read debug information files.

Available from:

Frank A. Vorstenbosch's cross-assembler page.

Older links are:

   - /SimTel/msdos/crossasm/as*
   - /computing/systems/ibmpc/simtel/msdos/crossasm/
   - and other Simtel mirrors.

We produce a 6809 C cross compiler. E-mail me for more info (fax number
is useful) or in the USA contact Avocet Systems Inc. on 207 236 9055.
 Clyde Smith-Stubbs       | HI-TECH Software,       | Voice: +61 7 300 5011      | P.O. Box 103, Alderley, | Fax:   +61 7 300 5246
 ...!nwnexus!hitech!clyde | QLD, 4051, AUSTRALIA.   | BBS:   +61 7 300 5235

I offer a low cost 6809 Development package. Includes C compiler,
Assembler, Debugger, Library source code, Integrated Dev. environment
+ command line tools. EMAIL for more info.
Dave Dunfield (    Embedded system development tools
Dunfield Development Systems  Box 31044  Nepean Ontario Canada K2B 8S8
Tel: 613-256-5820   Fax: 613-256-5821   BBS(v32/v42/HST): 613-256-6289

Introl manufactures a line of C cross-compilers and source-level debuggers for Motorola microprocessors and microcontrollers. Our compilers and the processors they support include: 6809/8HC11/6801/6803/68701/6391/6303/68HC16.

Each C Compiler system:

For more information, contact
An In-Circuit Emulator is available from a company called Pentica. The model is MIME and it supports emulation for the 6809, 6803, 6801. There representative can be reached at:
        Pentica Systems, Inc.
        19A Crosby Drive
        Bedford, MA  01730

        Phone:  (617)275-4419
        Fax:    (617)275-6514

A 6809 assembler and a Simulator:

You'll also find my C++ mc6809 simulator in the same directory.

R. P. Bellis                            E-Mail:
Computing Officer
MRC Centre in Brain and Behaviour
Dept of Experimental Psychology
University of Oxford
South Parks Road                        Tel:    +44 1865 271359
Oxford OX1 3UD                          Fax:    +44 1865 310447
Editors comments: This site appears to be down. I've made a Local copy
JM Micro has a 6809 single board computer, EPROM emulator, and Universal Microprocessor, and a Simulator/Debugger., or

Look particularly into subdir /mcu (Ray Bellis) writes:

>If you've got a Unix or DOS system with a C++ compiler then you could
>get hold of my (free) simulator from:


I *highly* recommed Ray's setup --

My friend Brian and I have used this as a core of a *successful* 6809
based emulator for Williams pinball machines ...

Minor modifications (are you interested in a copy, Ray ?) allowed it to
run the 6802 code Williams' older System 11 based games run and we're
currently figuring out the addresses for the newer WPC based games ...

One question -- we're confused on how Carry is used particularly on
adds, subtracts, and compares on the 6809.  We've finally gotten the 6802
set correctly, but we're worried there may be some bugs on the '09 code ...

Ray ?

- Jonathan
--    |  "I Hate it when I can't trust  | Atlanta 1996 !!            |   my own technology!" - LaForge | Play Pinball !!

In article <2r9v12$>,
Lennart Benschop  wrote:
>In article <2r7825$>,
>Lennart Benschop  wrote:
>>New version of 6809 assembler and simulator coming soon.
>>Recently I managed to improve both the 6809 assembler and the simulator
>>slightly. I will post the stuff to alt.sources later this week. The 
>>programs are known to work on several UNIX platforms. 
>This was just posted to alt.sources in 3 parts.

  It's now available at:

Lennart Benschop ---

OK, I promised I would make available the Assembler/Linker and its
available. I put it in the directory /pub/incoming
I don't know how long it will stay there, most likely it will be moved
to another directory. The file is the DOS exe files (SCCAS09.EXE,
AS6809.EXE, AS6811.EXE, and ASLINK.EXE) it also contains a text file describing
how to use it. The source is in xasm.tar.Z, this is mostly useful to all the
Unix people out there who can compile it. Any questions, email me at

Neil Cherry

From: "Michael Evenson" 
Subject: 6809 emulator
Date: Tue, 5 Jan 1999 06:20:11 -0500
MIME-Version: 1.0

Hi Alan,

    I was looking at your updated 6809 web page and noticed that you
now have a link to the Ben Williams (Blish) 6809 FLEX emulator.  It
set me to wondering if you could add a link to my home page for the
SWTPC 6800/6809 emulator. It already runs OS9 (the SWTPC version).

  I can't distribute it over the internet OS9 that is), but I can
provide the OS9P1 ROM if someone already has the OS9P2 ROM. With that
and a regular OS9level 1 boot diskette image, the emulator runs Level
1 without ANY problems.

  Ron Anderson is using it at his place of business to maintain legacy
6809 code for embedded controllers instead of trying to maintain their
old 6809 development boxes. He says, it's getting hard to find parts
anymore, and with the emulator, as long as you have a PC that runs,
you can still run all of the old FLEX and OS9 development software
that ran on the SS50 bus computers.

  You can download the emulator from my home page. There is also a zip
file of the 6800 and 6809 boot diskettes. Check out the Quick start
quide (unfinished, but informative). I've made quite a few
improvements to the emulator since last year.

The url is:

    Michael Evenson

From: Ben Williams 
Newsgroups: comp.sys.m6809
Subject: 6809 Flex emulators for Win95 and AmigaDOS 2.04+ available
Date: Fri, 24 May 1996 02:18:31 -0600
Organization: Black Belt Systems

Hi folks.

If you're interested in a full-blown 6809 emulation for Win95 or
for the Amiga, see:

Includes asm, editors, utilties, etc. Check it out.

Ben Williams
Editors comments: This appears to be a flex-specific 6809 emulator. Discussions with Ben indicate that he's trying to add OS-9 support to the emulator. More news as it progresses.
This wouldn't be complete without a push for my own 6809 system. Along with Boisy Pitre, I've written a 6809/6309 OS-9 assembler (xasm), a simple emulator (ocem), and a few other utilities.

The assembler can create output in a number of formats, including OS-9 modules. The emulator can run OS-9:6809 programs, and then trap and emulate many of the OS-9 system calls. This means that it's possible to run many of your favorite OS-9 utilities again!

Everything should be available as images from the latest version of the source tree. See:

Alan DeKok.

Related Topics

( more from comp.sys.m6809 posts)
The 6809 has two stack registers and a buttload (using the technical
term) more allowable stack/index/offset operations (e.g.  leas, pshs). 
This makes life a bit easier for doing a gcc port of the chip.

The latest version of the port I did for the 6811 can be found at:

You should also get the original distribution for gcc-2.6.3 from your
favorite archive site.


Otto Lind                  Coactive Aesthetics          P.O. Box 425967, San Francisco, CA 94142
netcom!coactive!otto       voice:(415)626-5152    fax:(415)626-6320

Although not free, ImageCraft sells a full featured (including floating point!)
compiler for $45:

    P.O.Box 64226
    Sunnyvale, CA 94088-4226

    (408) 749-0702
further details

Jeff Vavasour's Radio Shack Color Computer 2 Emulator can be downloaded for free. It will run OS-9 Level I, and emulates the SAM (6883), VDG (6845), and PIA (6821) chips, along with the 6809 CPU. Included in the archive are instructions for getting the Coco 3 emulator, which costs $$.

If you don't have your Coco up and running, the ROMs are available in the UK. These are copyrighted, so you won't find a version locally.

The 6809 software developer's archive has lots of interesting 6809 things.

There's another free 6809 assembler and simulator for Linux, at

Last updated: Mon Jan 4 14:08:30 EDT 1999 by Alan DeKok