Editron and Sontron S-100 systems

This page last edited Jan 19 2011 updated Nov 11 2021 (c) 2021 Herb Johnson
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[Editron 500 system] Editron was an Australian company founded by Graham Thirkell in Oakleigh, Victoria; with US facilities in Hollywood, CA. They produced some S-100 based video control and mixing systems in the mid-1980's. System names included Editron 200, Editron 500, Editron 520, Sontron, and a Telecine video editing product. Not all of these cards were S-100. They connect to videotape decks, time code generators, and to typical computer items like keyboards and displays. These audio editing systems were used by many professionals to edit sound for movies and videos for many years.

Graham Thirkell has a substantial history in both 1970's microcomputing, and in audio recording and broadcasting for which he recieved many awards. Search the Web for his role in PBS 106.7FM", a public FM station in Australia; his Optro company in Australia; the AES; and various good remarks about him from audio recording experts, on studios he designed and his other works. As of the late 2000's he apparently retired; he passed away 6 April 2010.

Documentation list

[Editron 439 CPU card] [Editron 503 RAM card] In Aug 2009 we recieved a few sets of documentation for the systems listed above. Thanks to Patrick Roberts for providing these, read Patrick's comments about his system. Here's a list of specific boards by model number and function. typically I'll have a schematic, a board layout diagram, and a few pages of technical description. There are also document for cabling, either system cables or specific cables to specific brands and models of video devices - tape decks and such. Not all card and cable docs are listed. We'll provide page counts and a price for a photocopy per product, when requested. See my email contact page for more information and how to contact me.

Note: the docs refer to a "DJ2D" card. That's a Morrow floppy disk controller card, check my Morrow page for details. It's possible some cards used in these systems, were similar to or actually bought from other S-100 companies.

Card documents, Editron 500 binder:

323 - relac comp card
439 - single card computer board
462 - 
502 - sync card
503 - RAM card
630 - octal VCA card
634 - time code and communications card
468 - keyboard matrix
240 - time code reader
322 - interface card
548 - singl card interface
598 - system clock and baud rate
599 - loop communications
439 - SSCC card

Card documents, Editron 520 binder:

647 - 20 channel relay comparator
439 - single card computer board
462 - video card
635 - modularity card
502 - sync card
503 - RAM card
630 - octal VCA card
634 - time code and communications card
658 - multistand sync card
639 - singl card interface (1987)
599 - loop communications
598 - system clock and baud rate
1004 - quadrature modularity card
505- keyboard interface
468 - keyboard matrix
545 - IBM Xt keyboard connector

Editron 200/500A Software descriptions
ROM descriptions
"What is an Editron?"
MSYNC program listings (ASM)

11 X 17 schematics for:
540 - A/V machine interface
634 - time code

black binder:

Editron 600 VT system operating instructions, 1989, about 70 pages
Editron 500A/200A softwar descriptions, 11 pages
Single card interface software descriptions, 11 page 1987
Editron description, installation and software, 1987, 25 pages
Cromemco Z80 monitor document, 7 pages
Editron CP/M (looks like generic CP/M description)
Sync/comm card notes (1987)
Debug documents, 17 pages
CMX 3600 operation documents - well over 100 pages

A Editron card surfaces in 2021; more Web presence

[Editron 639 card]

In November 2021, a vintage computer owner in New Zealand, Lord Philip, was given a Editron board. "Although the board states it's an 'interface' card, it has a Z80, RAM etc which makes me think it could be a SBC." Inspection shows it's a 639 "single card interface" board. The local Z80 chipset on board, permits operation of a 1980's video tape deck through a video-standard controller connector. It's apparently tied to the S-100 CPU board through external serial connections. The S-100 bus apparently provides some handshake signaling, probably for events. The card is missing some chips including a ROM, but retains the PALs which decode addressing and signals.

I took the occasion to check the Web for more Editron information. I found an Australian museum devoted to domestic video audio equipment. In New South Wales, the Museum of Applied Arts and Sciences shows an Editron system with this description: "The Editron is a computer based synchronisation system designed for use in an audio production environment. Editron was an Australian company founded by Graham Thirkell a legendary figure in Australian audio engineering and acoustic design. This Editron [200A and 500a and CPU in the collection were] used at the AFTRS for training post production technicians in its operation and in the development of student works. - Campbell Bickerstaff, 2010".

From the Audio Engineering Society, Melbourne Section, is an article "Graham Thirkell: Clippings'n'Photos". The news clips discuss Thirkell and the Editron as sold by Sontron Instruments Pty Ltd in May 1986 to Los Angeles CA USA based video production company Pacific Video.

At archive.org's magazine collection, Electronics Australia Oct 1987 magazine page 44 has a news brief: "News Highlights: Big sales for locally made editing gear" as follows:

Australian developer and manufacturer of audio, video and film editing equipment, Sontron Instruments anticipates being able to establish distribution agencies in Europe, Japan and Canada, following equipment sales worth $2 million during July.

Managing director Graham Thirkell says that more than 55 of the firm’s Editron synchroniser editing systems have been installed in film video and audio production houses in Australia, then USA and Hong Kong, most in the last 18 months. An extensive marketing drive is currently under way in London.

The technically advanced Editron systems have been used in the production of “Crocodile Dundee”, “Light Horsemen”, “Australian Made”, “Mad Max”, and “Ground Zero”. They are used by AAV Australia, Film Australia, Soundfirm, Australian Broadcasting Corporation, ATV10, TCN9, Video Corporation and many others in Australia. The Editron is also used in the preparation of CD Masters in Australia’s only CD plant, operated by Disctronics, a subsidiary of Pro Image Ltd.

Patrick Robert's Editron 200 system

I corresponded with Patrick Roberts in August 2009, after he posted some information in Usenet newsgroup comp.os.cpm. Here's what he told me about his acquisitions, including his comp.os.cpm posts. He provided his extra manuals to me: Thank you. - Herb Johnson

[Editron 200 system] I have a box full of manuals, I haven't had a chance to go through them yet. They're for devices called "Editrons", but they're for "Series 500" and the board I have says it's Editron Series 200. Hopefully parts will be similar.

The case cover and front and rear panels are missing (if it had them to start with.) The base looks like a large rack tray with air vents around the raised edges. Judging by the design this tray was not designed to be the main or only support structure. It has a sticker that says "TOP COVER", which if correct means the S-100 backplane is top-mounted with the cards hanging down. The layout of the internals is very similar to the IMSAI 8080.

Two 5.25" floppies are mounted vertically in front of PSU. It has a AED [Morrow] DJDMA controller for the floppies. There's a 50-pin centronics (?) cable coming off the board but whatever it went to is missing. The rest of the cards are...

SONTRON "PC-503 Issue 2 64K Memory Card" populated with MOSTEK RAM;

SONTRON "PC-461 Issue 2" card, has a Motorola MC6845P "Non-VGA video controller" chip. It also has a daughter card attached: SONTRON PCB-635 "RGB Video Modularity Card".

SONTRON "PC-502 Issue 2" card. No other labeling, but has a sticker that says "NTSC MODS". Attached to the PC-634 card that follows the CPU card.

SONTRON "PC-439-3" cpu card says "Single Card Computer" on the back of the PCB. Has the following Zilog chips: Z8430APS Z80A CTC, Z8470APS Z80A DART, Z0840004PSC Z80 CPU

SONTRON "PC634 Issue 3 COM/TIME CODE GENERATOR" Connected to the PC-502 by two jumpers. Has an Intersil IM6402IPC serial interface chip.

The S-100 backplane board is marked "PC-562-2"

Three of SONTRON cards have top jumpers with cables running along the center card support to (probably) the rear panel, when it had one. However all the connectors have been snipped off, so I have no idea what type of ins/outs they may be.

[About researching the company,] I did find a business partner of Graham Thirkell who was mentioned in a post. I sent him an email asking about SONTROM and Graham asking if he could pass my email address on to Graham. The response I got back was "Graham owned sontrom. He is now retired. Regards."

I asked a friend who's been a video editor here in Hollywood for years if he knew what an Editron was. He remembered it being some system that you'd hook up 20 VHS decks to and you could get close to random access audio or video. When a song or video segment (commercial?) was requested, the Editron would find which deck was closest to the timecode requested, locate the timecode on that deck, and switch an output matrix to that device on queue. This one I have looks like it was for audio, so maybe it was sort of like an iPod circa 1987.

The system [I acquired] is a Editron 200A host made by Sontron sometime after 1987. Board design docs span 1984-1987. It's a single-rack-box audio system that could control 5 VTRs. The 500A is close to the same thing, but was two rack mount boxes and could support 15 VTRs. The system I have is missing the VTR interface break-out box, transformer, the keyboard control panel, and I think the VTR relay control card...need to look a little more at which pieces the 500A had that the 200A didn't. According to the 500A manifest, there's 3 cards I don't have in this 200A (Octal VCA card, 8-channel comparator, 20-channel relay card).

I have 4 manuals: Two copies of "Editron Audio Production System Model 500" (500A) - which I think goes with the unit I have. "Editron Computer Assisted Video Editing System Model 500V", and "Editron 520" - Not sure what the 520 is, but it appears to have been attached to a Rank telecine machine. All have lots of schematics and block diagrams (hand-drafted!). - Patrick Roberts

Notes from Richard Thwaites

in a follow-up post in comp.os.cpm, Richard posted the following, here with permission. - Herb

I can confirm that Sontron was one of the brands used for professional sound studio equipment made in Melbourne, Australia by companies led by Graham Thirkell, an outstanding innovator in electro-accoustic fields from late sixties analog tape gear through to contemporary accoustics testing. Other brands he used were Editron and Optro. He still practices as an accoustics consultant. I understand he stopped building equipment as the market grew more crowded and imported from elsewhere.

Don't be surprised at the origin - the world's first digital sampling synthesizer was also Australian - the mid-70s Fairlight. Stevie Wonder bought one as his introduction to sampling, and set off the whole idea of sampling that is so prominent in progressive music. [Wikipedia has a discussion of the Fairlight.]

Thirkell passes away in 2010

The 20 Sept 2010 edition of the Australian Screen Sound Guild's newsleter reports that Graham Thirkell passed away 6 April 2010. An obituary was published April 9, 2010 in the Australian Herald Sun newspaper.

[Dave Swann, a former employee of Graham Thirkell, told me of Graham Thirkell's death in Jan 2011, and said the following:]

"I worked there for several years, and I'm still in contact with a few of the other guys. [Graham] was extraordinary. Before the Editron days, he designed and built 24 channel audio 2-inch tape decks."

"A bit of trivia is that the audio mixing for Return of the Jedi was performed using an Editron by Rodger Savage [working as] the company Soundfirm. I understand that the Editron that Rodger used was the first one - I think it was his idea and Graham and the other guys designed & built it. [But] it was before my time."

[note: Return of the Jedi was released in 1983. - Herb]

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Herb Johnson
New Jersey, USA
email me @ my ordering Web page

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