As an Acorn Electron officiando of many years now, you might think I had nothing left to learn. Hardly. For there are a number of questions about the machine that remain unanswered even to this day. For example, what happened to the Acorn Plus 2, an extension reported to contain an RS423 port for connection to a modem? And I'm not talking about Pres' later Advanced Plus 2 ROM. That was a different product entirely.

Well, I would like to introduce you all to the British Telecom Business Systems M2105 Messaging Terminal expansion that I recently bought for the tidy sum of £150. The same breadth as the Electron but stretching back twice as long, this beige-coloured interface is an official Acorn Computers product that may well be The Missing Link in the whole Acorn Plus 2 puzzle.

Over the years Electron User and EUG have been around, more than a few sporadic reports regarding this mysterious interface have been made. My predecessor mentioned a network of Electrons with what he called Plus 2s being hooked up once in a hospital where he worked; a reader mentioned having an Acorn "Merlin" machine as well as an Acorn Electron in his computer shed. Others told stories of seeing such machines in their local florists; one EUG member also recalled a conversation he had had with a BT engineer whose job it was to fix them.

I suspect now that all were talking of this particular extension; the whole unit of Electron plus Merlin interface being known as both an Acorn Merlin and a BT M2105 Comms System. It seems they were never offered for sale to the general public, at least not through the Acorn magazines anyway. Instead a number of "terminals" (Acorn Merlins) were able to communicate with each other via the network of telephone lines, by sending ASCII characters to one another via the connector on the back. For most businesses that bought them, I assume they were an expensive experiment. Still, to avid collectors such as myself and whoever it was bidding against me on eBay, what a find!

Gingerly taking out the Acorn Merlin from its original polystyrene, there is no doubt that this product was never sold in two separate 'chunks'. The Acorn Merlin, consisting of Electron and Merlin expansion, came already screwed together. This particular model has a yellow sticker (of the same dimensions as the acorn electron one) pasted above the top row of the keyboard reading "The Interflora Messager". Ah ha, the florists! There are also some very brief instructions on the effects of CAPS LK/FUNC with the keys ESCAPE along to Cursor Right.

I come to the unfortunate part of the story now. Although the Acorn Merlin seems to work fully, I have no instructions on how to use it and can't think of anywhere where I might find them. I have gleaned from 8BS that it is capable not only of transmitting information through its internal modem but also of speech synthesis, and a sticker on its base mentions an extra 32K CMOS RAM is installed. But all of this I can neither confirm nor deny. All I had to guide me in using it were on the on-screen menus, and options like "rxhst", "pendg", "jrnal" and "s/o" do little to help.

First things first though. Switching on brings up on screen the message "Merlin Business Systems, M2105 Terminal 1, Version V4.21 13/05/86, (c) British Telecommunications plc 1985" and then one character at a time "scE120E120". You then get the familiar beep of the Acorn Electron on power up.

The Merlin takes over the whole of the Acorn Electron and I couldn't find any way to break out of the communication software and use BASIC. The Merlin also ends at the rear with only a socket for a printer and a, well um, something else. This unit was not meant to be expanded with a disc drive it seems.

On screen now you are asked to input the time, the date and the telephone number, the cursor moves on to the next piece of information after you type the last digit in each. "Now press COPY and select SO unless further changes are required" a message runs underneath this information. But COPY brings up not "SO" but "S/O". Presumably this is the same thing ("Save Options" possibly?) as, after doing this you get the display updated in inverse video with the date and time you entered.

The system runs in Mode 0 with only two CHR$ definitions of a telephone and a "/|/" (toggled by pressing the ESCAPE key) in the bottom left hand corner. ESCAPE evidently toggles between "input data" and "send data" respectively. Of course, I don't have another Acorn Merlin in another house to see if I can send anything between machines but the indications are that this is still possible.

The menu options "SEND, INDEX, FORMS, DELETE, COPY, S/O" also allow you to access a Mailbox and a Notepad where you can type simple text word processor style into a Registration Form or simply onto the screen. A bit of twidding with the keyboard revealed FUNC pressed in combination with certain keys made editing more simple. FUNC-W pages the form/text down; FUNC-E back up; FUNC-D deletes the character under the cursor; FUNC-F moves forward in a form; FUNC-B moves back and FUNC-S moves to the very start.

There is also a clipboard option similiar to those found in the leading word processors. You can move a data entry to it with FUNC-M, then move to another area and replace that information with it by pressing FUNC-R. You can select multiple areas and the first press of FUNC-R inserts the first "marked" information, the second inserts the second, etc.

Navigating the menus is fairly simple. A high pitched bleep tells you when you have made an invalid input and the cursor keys work as you would expect to select an option, as do the first letters of (S)END, etc. On the opening Set Time/Date screen, there are many more options that can be accessed with FUNC-W to page down and these include parity, "voice response", whether the modem noises can be heard, etc. Voice response, of course, sounds particularly intriguing if the machine does indeed have speech synthesis in there!

To date, this is as far as I really can progress with the Acorn Merlin but I have no doubt that this was the Plus 2 interface Acorn phophesised but ultimately didn't deliver. If anyone has a manual for it or indeed any more information at all, I would love to have it so please do get in touch. As an official extension made by Acorn Computers (and badged so), it certainly deserves a lot more recognition.

Dave E