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Original Sinclair QL related hardware.

Manufacturer: ICL / Sinclair / BT joint development

Item Name: OPD / AKA BT Merlin Tonto or Computerphone

Estimated Rarity (1 - 10): 6

Related Software: Psion Xchange within the BT branded expansion Rompack, Messaging within a BT branded ROM Capsule and ICL branded Microdrive cartridges containing BASIC, Welcome, Demonstration and Help. Also BT branded loose XCHANGE HELP.


Here's a little message spoken by the machine itself.

One of the world's first smart phones (but not in the slightest bit mobile*)? The ICL OPD also known as the BT Merlin Tonto or the Computerphone in Australia, New Zealand and apparently also Hong Kong.

It wasn't a bad idea at the time. A device that could be used to store hundreds of names and telephone numbers and would even dial those numbers at the touch of a few buttons. It could be configured to answer the telephone and speak a message, like the one linked to above. It had a basic messaging program that was something like e-mail before that became established, whereby OPD users could send each other text messages. It could also connect to servers and could be used as a terminal. Most also had Psion Xchange built-in (the grouped name for the familiar 4 Psion utilities that were bundled with each QL) so that covered word processing, spreadsheet, database and bar/pie charts and added a calculator, too. It also had a trimmed-down version of QL BASIC, so it could be used to write custom programs that could no doubt have performed tasks that were useful for whatever business or local authority it was used within - and it was solely a business machine, never really being marketed for the home user.

It flopped, some say due to the high price tag. The menu driven OS was a bit clunky and the 128k of RAM was woefully low. It wasn't compatible with any other computer either (something that wasn't unusual for computers in the mid 1980s) so even though it used standard Sinclair Microdrive cartridges, OPD cartridges could not be read by the far more useful Sinclair QL despite the fact that the drives themselves were virtually identical. A couple of types of disk drive were sold by 3rd parties a little later on, but I don't think the disks they generated were particularly compatible with anything else.... certainly the disk format used by the Computer One interface doesn't seem to get along with any other computer and I can't speak for the alternative and apparently better PCML Teledrive disk drive interface, as I've never tried one. The Teledrive also included 128k of extra RAM (+ CP/M capabilities) and there were also home-brew modifications to double the RAM to 256k, which certainly would been beneficial but it was the mid 1980s, things were moving fast and soon the IBM PC with MS-DOS became dominant within the target business user market. BT ceased support for their Merlin Tonto in 1993.

My own 'OPD' is actually the Merlin Tonto (
The Outstanding New Telecoms Opportunity!) variant, but that was just badge engineering, both machines were internally identical. Mine has been upgraded by me to include BASIC in ROM (otherwise you have to manually load it from microdrive every time and it eats up precious RAM) and it has a 3.5" disk drive, thanks to a Stephen Usher having reverse engineered the original Computer One device. I no longer have the original monitor, which also included the power supply for the computer - I got around this by adapting an old ATX PC PSU to provide the required voltages and the video is output via scart, which required an internal modification.

 *Not mobile, but my Tonto does actually have a connection with early cellular mobile phone technology - the London telephone number 01-378 7141 shown under the receiver belonged to the Network Planning Dept of TSCR (Telecom Securicor Cellular Radio) Ltd, AKA BT Cellnet. This Tonto would have lived at Hanover House, 49-60 Borough Rd, London, SE1 1DS.


ICL and BT branded cartridges.

ICL branded cartridge wallet containing BASIC, Welcome, Demonstration and Help.

BT branded box for 20+ loose cartridges (made by Transform).

Rear of BT branded Xchange expansion Rompack with messaging ROM capsule plugged into it.

Front of the BT Rompack. Note the 075 is a datecode, indicating July of (198)5.

Slightly yellowed BT 'Messaging' ROM capsule.

Page on QL Wiki (some more info here): https://wiki.qlforum.co.uk/doku.php?id=qlwiki:history

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