EXORset 30 Motorola development system

Most recent revision date of this page, Nov 1 2022. Copyright 2022 Herb Johnson. Some photos courtesy of Matt Jordan. Other contents courtesy of their authors and creators.



In Feb 2018, I obtained a EXORset 30 development system, Motorola 6809-based, from engineer Matt Jordan. He obtained it from another engineer who first worked with it in the 1980's. Thanks to them both, for preserving this system. In late April 2018, I brought The EXORset back into operation again. Here's the story. - Herb Johnson

System as obtained
Software and paper docs
Vaguely related 680X systems
Other EXORbus based systems
documents and software on other Web sites

System as obtained

I obtained this system in Feb 2018, from engineer Matt Jordan. Here's some background about it, courtesy of Matt:

"My co-worker who previously owned the EXORset, was working as an electrical engineer for a now-defunct tech company making custom computer components in the 1980s. Much of his work was done using P-CAD for logic simulation and schematic layout on IBM PCs. Management give him the unit, presumably after it was retired as they discontinued 6809 development projects. [It included] some [extender] cards for the machine that look like they are intended for prototyping and testing. He put the machine in storage, planning to get around to exploring it again, but needed to downsize in retirement. I worked out a deal with him to get a lot of his old equipment as he left the area."

"The [documents] binder itself has seen better days but I was pleased that it still existed. (I also really loved the over-the-top early 1980s artwork showing off the machine.) [Herb notes: I replaced the binder but migrated the documents.] When I first acquired the machine and I learned that it came with all that documentation, my interest level went up significantly! Because for a non-consumer computer that saves *MANY* hours of poking around. The schematics especially! Since these machines were used almost or entirely by developers, I figured that the few copies that did exist were lost to the dustbin of history.

I found (and include) some printed source code that I assume was written on your EXORset and there is a note with the floppies showing correspondence with Motorola. The letter seemed to indicate that some of the software on those floppies is an unreleased beta/preview of a yet-to-be shipped package. That could actually be the only copy that still exists, at least outside the archives of Motorola."- Matt Jordan

Matt went to considerable effort and expense to pack and ship the unit to me, as part of an exchange. Thanks to him for passing this system along, and to his co-worker for preserving it. - Herb Johnson



Shipping was a considerable effort, as the unit packed was almost 70 pounds. It was bagged, then boxed with surrounding expandable-foam padding. Some brown-paper was bunched to fill the void in front of the CRT. The box was banded and the bands taped. Packing was performed by FedEx.

EXORset unpacked
EXORset unbagged
EXORset docs


The system is a Motorola 6809 on a "populated" motherboard with a backplane supporting Motorola's EXORbus (EXORciser bus). Processor, ROMs and some I/O, 16K RAM, and video, are on the motherboard. The bussed floppy controller also has 16K of RAM. The bussed RAM card can hold 64K of RAM but is populated for 16K. The complete system has 48K of RAM and some amount of ROM to fill the 64K memory map.

The rest of the system is typical for 1980. Non-switching power supply. two Qume DT5 5.25-inch double-sided floppy drives. Keyboard is likely parallel interface. 9-inch CRT. Looks like the rear has PC board pins for a serial and a parallel interface, one supports a printer. At first look, the paper documentation covers the hardware including schematics. two original diskettes came with the system.

The EXORset 30 hardware, ROMS and their operation is documented in a thick manual, "EXORset 30 User's Guide" MSET30(D1) from 1980. It's bound and tedious to copy. But I copied out about 30 pages of pure hardware description. Here is some of the hardware of the EXORset 30 less the power supply, floppy drives, CRT monitor which are also documented. Here's an additional set of schematics from the paper docs. I did not copy the monitor commands and diagnostic commands. EXORbus documentation, particularly for the 6809, was not very available as of 2019; this is a start.

- Herb

EXORset front
EXORset logo
EXORset side
EXORset top
EXORset rear connectors and I/O
EXORset drives

EXORset extender cards
EXORset cardcage
EXORset floppy controller
EXORset RAM card
EXORset PB1 adapter card

EXORciser Bus, EXORbus

The bus architecture for the EXORset 30 is based on the Motorola M68SDT EXORciser development system of 1976. Simply called "the EXORciser's bus", it was a means to provide boards for each microcomputer function - processor, memory, I/O - to reduce costs of a development system and permit expansion (more boards) in the future. In the mid-1970's, all these things were either expensive or not-yet-available; program storage in 1976 was paper-tape or audio cassette. Here's some documents on the 6800 EXORciser's bus of 1976: the signal descriptions; and the pinouts from the 6800 CPU board.

Here is the hardware of the EXORset 30 from the EXORset 30 user's manual, which I've not completely copied. By 1980, Motorola called their architecture the EXORbus, and they described their 6809 implementation in this manual. - Herb

I've colated the 6800 and 6809 bus signals in this document. The EXORbus in the EXORset 30 has a handful of signals not on the 6800 EXORciser card.

Software and paper docs

With my system I have these documents, scanned as of April 2020:
EXORset 30 XDOS Operating System Users Guide Mar 1980
EXORset_Users_Addendum is an addendum April 1981 to the above Users Guide
Qume_DT5_Maintenance Manual is part of that Addendum
EXORset schematics were loose schematics included with my EXORset 30 system
EXORset Pascal brief document

Manuals I have not yet scanned (perfect bound not loose pages)
EXORset 30 User's Guide March 1980
EXORset 30 XDOS Assembler User's Guide March 1980
EXORset 30 XDOS Editor User's Guide March 1980
M6809 BASIC-M Interactive Compiler User's Guide March 1980

Here's the intro chapters of the XDOS 3.0 manual; it's quite large. The first few pages of the User's Manual describes the system. It runs Motorola's XDOS diskette-based development OS. In Apr 2020 I scanned the full manual; ask me for a PDF, it's too big to host on my site.

Software was on a "BASIC" diskette, and there's three "PASCAL" diskettes. As Matt noted, the paper docs describe the hardware and the ROM monitor and BASIC. I did not obtain PASCAL manuals with this system, I did obtain some BASIC manuals. Here's some PASCAL notes from the paper docs.

Documents and software from Frederic Le Duigou

I was contacted in March-April 2020 by Frederic LeDuigou, in France. He's working on emulators for a number of 6809 systems of the early 1980's; he has a number of them which he's restored. He also has an EXORset 30 system, and later versions of XDOS and related software and manuals. Mine are from March 1980; his are from 1982. He's scanned his documents and imaged many XDOS diskettes; some items were apparently obtained from JB Emond in 2018. He's allowed me to make them available. I'll not put them on my Web site but one can ask me for copies.

Since early 2020, Frederic has improved his emulator and it's available from his Web site, in French. Not all of his scanned and imaged documents are available on his site, you can ask him for specifics. [In 2022 I updated my links to his site.] - Herb

Correspondence, April 2020


I contact you because I started to make an emulator for the ExorSet 30/100. I have the documentation for that with the 3 machines that Iíve got a few years ago, and a set of EPROMs and floppy images.

Iíve succeeded to load the XDOS system from the floppy, but I have some trouble now because I donít have the right manual. Mine is dedicated to the XDOS4, but the floppy images have the EDIT and XASM software, that are dedicated to the XDOS3 (as far as I understand).

Concerning the GROUP 3 [files and documents on my Web site],youíll find some picture here [on another Web site]. This computer has been designed by a french company at the time of the rise of the computer at school. The company was highly sponsored by the government and developed a very powerful computer based on the MC6809.

The first and the second of the family (GOUPIL 1 and GOUPIL 2) were based on the MC6800, but the GOUPIL 3 was really very good : - MC6809 at 2 MHz - 256 Kbyte of memory with a memory translator to fit with the 16 bits bus of the processor - 2 8íí floppy an 2 5,25íí floppy - One HDD 5 Mbyte - B/W and Color display - MODEM board for TRANPAC access

This computer was I think inspired by the SWTPC 09 (or reverse, I donít know !) The company added a secondary CPU board that could be Z80 or 8088. When the IBM PC came, a version of the GOUPIL 3 was running a pseudo MSDOS, but not fully compatible. The production cost killed the company when the low cost PCs came from Asia Ö I have 3 GOUPIL 2 working, and 2 GOUPIL 3 but only one working ...

- Frederic Le Duigou

Paper documents as PDFs

EXORset-CHAPTER*	from EXORset User's Guide June 1982
EXORset-Appendix*	from EXORset User's Guide June 1982
				not including App D power supply
EXORset-MDOS LINKING LOADER	reference manual Sept 1979
EXORset-MACRO ASSEMBLER*	M680X reference manual Sept 1979
EXORset-CRT EDITOR.pdf	reference manual Dec 1980
EXOMON5_LST.TXT		assembled listing of two CPU EPROMS  
				(not including floppy controller EPROM)
				JB Emond 2018, English 

XDOS 4.0 User's Guide	XDOS 4.0 June 1982

EXORSET Plot package reference manual June 1982

BASIC-M Interpreter / Compiler User's Guide June 1982

I [Herb Johnson] have similar documents but the 1980 versions.

disk IMG images, EPROM dumps

There are about 25 imaged XDOS diskettes, as IMD (Dave Dunfield IMAGEDISK format) files. "Saved by JB Emond 2018". Single sided single density, 40 tracks 16 sectors of 128 bytes interleave of 2:1.

J B Emond

Duigot provided a set of EPROM dumpsas obtained from JB Emond 2018. J B Emond has a Web site with photos of a disassembled EXORset And the disk images are at this Web link. The PROM imagesare at this link.

Restored to operation, April 2018


There was a repair weekend on April 28-29 2018, at the Vintage Computing Federation's museum in Wall NJ I brought the EXORset system in on the 29th to test and bring it up from its dormant state. That statement is literally true. As the photo shows, there's a Variac to the left of the system, the grey cylinder with black knob on top. It varies the AC voltage supplied to test devices, like today's EXORset system. It's necessary to "reform" the power capacitors in the (non-switching) power supply, by gradually increasing the voltage to them. That gives the old electrolyte time to "reform" and not blow itself apart. For convenience, I monitored the 5-volt logic-power voltage, from one of the floppy drive connectors. About half an hour or so of stepping up the AC voltage, did the job.


So when the power supply was able to operate at near-full voltage- 5 volts - I pushed the hardware reset button on the back, adjusted the CRT brightness, and saw the ROM monitor prompt on the screen as shown: "EXORBUG 1.2A". [Later, my wife squinted at the photo, and said, "Doesn't that say "error"? ;)] I grabbed the User's Manual and looked for the correct monitor commands - most of my guesses got the response "WHAT?". An immediately useful command was "PRNT" which provides a hexadecimal dump of the screen.

So, some commands showed me that most of the hardware was operating; but they did not test the Qume floppy drives. Before trying to read any diskettes, I obtained a long cotton swab and alcohol, to reach inside the drives to clean the heads. There's a danger that junk on the heads, will scrape off the iron oxide of the diskette surface, of course destroying the content. I was lucky to get some original disks with this system; I wanted to avoid risks. Inspection of the heads confirmed, they were double-sided, which doubles the capacity of the diskettes. Cleaning them was uneventful.


So, I inspected the "BASIC" disk I had, saw there was no mold on the surface after rotating the media in my hands. I put the diskette in the drive that responded to tests (on the left, the LED came on previously). The manual says the monitor command "XDOS" will boot the system disk. I entered it; the drive lit; I could hear the diskette rotate and the heads move. A minute of activity; pretty long. Then, the OS showed the XDOS 4.11 message, and then configuration of the drives, and gave the system prompt "="!

The BASIC disk had a few command programs - DIR, a diagnostic - but not critical commands like "FORMAT" for formatting new diskettes. There was a BASIC command, which apparently is a BASIC compiler, not an interpreter. Fortunately, there was a set of "PASCAL" diskettes, which included a disk format program and a disk-copy program. I obtained a blank 5.25-inch diskette from my friend Jeff Galinat, and successfully duplicated the PASCAL OS diskette. That was enough work for the day on this system - more success than I hoped.

- Herb

Related 6800, 6809 systems I have/had

Vaguely related, is a Motorola 6800 D2 card I had in 2015.

Also vaguely related is a STWPC 6800 SS-50 system from 2009.

other EXORbus cards, other owners

EXORbus cards I have which are not part of the EXORset 30 system.

EXORbus intercept module Says "Intercept module, System Analyzer 6809, M6809SAPR 1979". Looks like it intercepts bus signals, the card in test plugs into it.

I obtained some time ago, an EXORbus 6809 board. This is not part of the EXORset system - that system has a 6809 processor on the motherboard. Look at the 6809 on this board. Says "MC6809L 7F7920". The PC board also has a 1979 date. When was the 6809 produced? Well, there's a Byte magazine article in 1979. So this may be an early processor chip.

I acquired in March 2018, two EXORbus prototype boards.

other EXORbus owners, designers

In Dec 2019, Neil Cherry is gathering documents on those and other EXORbus boards on his home automation Web site. I have more about Neil's EXORbus interests on my Web page of other people's EXORbus works.

Stan Ruppert contacted me on July 29-30 2019. He's restoring two Matrox brand graphics cards ( exo-2480 and exo -512 ) for the Motorola exorciser system. He contacted me for my s-100 alt-2480 and alt-512 documentation. I have more about Stan's work on my Web page of other people's EXORbus works.

documents and software on other Web sites

In late 2022, I was contacted by a person, who hopes to provide "Dragon" source code as developed on an EXORset 6809 system under MDOS 3.0 with RASM09. I hope to provide details when that preservation work is completed. Dragon is a UK product line of 6809 computers like the Radio Shack/Tandy Color Computer. Dragon details are found at sites this UK site for Dragon and other 6809 resources.

Looking around the Web in 2018-19, I found these documents:

Something at computinghistory.org about the model 30
related Motorola docs at Dublin's Trinity College. However these are not online, but physically archived.
A Web domain about EXORbus stuff, FDOS, and more, in Finland!
A 6800 simulator "exorsim" on github
a SWTPC FLEX site at evanson-consulting. FLEX is a 6800 or 6809 OS in the SS-50 bus world.
bitsavers.org has some Motorola software but it is MDOS and OS9, not XDOS. It's not likely configured to operate on the EXORset.
An older Motorola EXORcisor system, packaged in a simpler cabinet. It has a lot of hand-wired cards and apparently some custom boards too. It's at a Holland museum, so English speakers can use Google Translate for an English rendering.

Herb Johnson
New Jersey, USA
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Copyright © 2022 Herb Johnson