Editing Acorn Electron (section)

===Merlin M2105===
An unusual variant of the Electron was sold by [[British Telecom]] Business Systems as the BT Merlin M2105 Communications Terminal, being previewed by British Telecom at the Communications '84 show.<ref name="acornuser198407_m2105">{{ cite magazine | url=https://archive.org/details/Acorn_User_1984-07_OCR/page/n10/mode/1up | title=Radio cell option for micros | magazine=Acorn User | date=July 1984 | access-date=18 March 2021 | page=9 | quote=British Telecom had the Healthnet terminal on show. This is an Electron with a custom-made expansion box, and it is intended for use where a lot of form-filling is done at many separate sites. }}</ref> This consisted of a rebadged Electron plus a large expansion unit containing 32&nbsp;KB of battery-backed RAM (making up 64&nbsp;KB of RAM in total), up to 64&nbsp;KB of ROM resident in four sockets (making up to 96&nbsp;KB of ROM in total), a [[Centronics printer port]], an RS423 serial port, a [[modem]], and the speech generator previously offered for the BBC Micro.<ref name="acornuser198406">{{cite magazine |url=https://archive.org/details/AcornUser023-Jun84/page/n8/mode/1up |magazine=Acorn User |title=Healthy link for Acorn |date=June 1984 |access-date=8 October 2020 |page=7}}</ref> The ROM firmware provided [[dial-up]] communications facilities, text editing and text messaging functions. The complete product included a monitor and dot-matrix printer.<ref name="electronuser198503" />

Initially trialled in a six-month pilot at 50 florists, with the intention of rolling out to all 2,500 members of the UK network,<ref name="electronuser198503">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume2/Electron-User-02-06/page/n4/mode/1up | title=Say it with Electron flowers! | magazine=Electron User | date=March 1985 | access-date=13 January 2021 | page=5 }}</ref> these were used by the [[Interflora]] florists network in the UK for over a decade.<ref>{{cite web |url=http://www.acornelectron.co.uk/eug/revs/bt/Merlin_M2105_002.html |title=Merlin M2105 | work=Acorn Electron World | publisher=Acornelectron.co.uk |access-date=12 January 2021}}</ref><ref name="chris_bt_m2105">{{cite web|url=http://chrisacorns.computinghistory.org.uk/Computers/BT_MerlinM2105.html |title=Chris's Acorns: BT Merlin M2105 |publisher=chrisacorns.computinghistory.org.uk |date=16 January 2008 |access-date=1 October 2015}}</ref> Used mostly for sending messages, despite providing support for other applications, limited availability of the product led Interflora to look for alternatives after five years, although users appeared to be happy with the product as it was.<ref name="electronuser198905a">{{cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-08/page/n4/mode/1up | title=Flower folk like their Electrons | magazine=Electron User | date=May 1989 | access-date=11 November 2020 | page=5 }}</ref>

This generic product combination of the Electron and accompanying expansion was apparently known as the Chain during development,<ref name="acornuser198406" /> itself having a different board layout,<ref name="chain_m2105">{{ cite web | url=https://stardot.org.uk/forums/viewtopic.php?p=58667#p58667 | title=BT M2105 Version | website=stardot.org.uk | date=23 February 2013 | access-date=6 March 2021 }}</ref> with British Telecom having intended the M2105 to be a product supporting access to an online service known as Healthnet.<ref name="acornuser198406" /><ref name="acornuser198505">{{cite magazine |url=https://archive.org/details/AcornUser034-May85/page/n128/mode/1up |magazine=Acorn User |title=Acorn reviews ABCs |date=May 1985 |access-date=30 August 2020 |page=127}}</ref> This service aimed to improve and speed up communications within hospitals so that patients could be treated and discharged more quickly, and to facilitate transfers of information to doctors and health workers outside hospitals, with communications taking place over conventional telephone lines. The service was to be introduced in the Hammersmith and Fulham district health authority, with installation starting at Charing Cross Hospital. The Electron was said to be particularly suitable for deployment in this application in that it had a "large expansion bus",<ref name="electronuser198406">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-09/page/n6/mode/1up | title=Electron to speed up NHS communications | magazine=Electron User | date=June 1984 | access-date=14 January 2021 | page=7 }}</ref> ostensibly making the machine amenable to the necessary adaptations required for the role, together with its "price, and the fact it has a real keyboard".<ref name="electronuser198405b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume1/Electron_User_01-08/page/n7/mode/1up | title=BT sign Electron boards contract | magazine=Electron User | date=May 1984 | access-date=14 January 2021 | page=8 }}</ref> As a Healthnet terminal, the M2105 was intended to support the exchange of forms, letters and memos.<ref name="btjournal198710">{{ cite journal | url=https://archive.org/details/btj-198710/page/n48/mode/1up | title=A prescription for healthy management | journal=British Telecom Journal | date=October 1987 | access-date=18 March 2021 | volume=8 | issue=3 | page=49 | quote=Healthnet is useful in hospitals and the National Health Service as a communications and information system. It transmits forms, letters and memos over the telephone as well as extracting data from the transmitted forms and turning it into clinical management information. Healthnet uses M2105 terminals. }}</ref>

The adoption of an Acorn product in this role was perhaps also unusual in that much of BT's Merlin range of this era had been supplied by ICL, notably the M2226 small business computer and M3300 "communicating word processor".<ref name="btjournal198307">{{ cite journal | url=https://archive.org/details/btj-198307/page/n67/mode/2up | title=Computer wizardry! | journal=British Telecom Journal | volume=4 | issue=2 | date=July 1983 | access-date=16 January 2021 | pages=34–35 }}</ref><ref name="bteng198307">{{ cite journal | url=https://archive.org/details/bte-198307/page/n73/mode/1up | title=First Electronics Office Products from Merlin | journal=British Telecommunications Engineering | date=July 1983 | access-date=26 February 2021 | volume=2 | issue=2 | page=132 | issn=0262-401X }}</ref> Nevertheless, the M2105 offered interoperability with other BT products such as the QWERTYphone which was able to receive messages from the M2105 and the [[One Per Desk|Merlin Tonto]].<ref name="bteng198701a">{{ cite journal | url=https://archive.org/details/bte-198701/page/n19/mode/2up | title=QWERTYphone - A Low-Cost Integrated Voice/Data Terminal | journal=British Telecommunications Engineering | last1=Durkin | first1=G. M. | date=January 1987 | access-date=26 February 2021 | volume=5 | issue=4 | pages=276–280 | issn=0262-401X }}</ref>{{rp|page=280|quote=Receives text messages from other QWERTYphones, Merlin Tonto and M2105 terminals or any terminal with a V.21 modem}}

The hardware specifications of the M2105, observed from manufactured units, include the 6502 CPU (SY6502<ref name="beebmaster_m2105">{{ cite web | url=http://www.beebmaster.co.uk/Elk/BTMerlin9.html | title=BT Merlin | website=BeebMaster | access-date=25 February 2021 }}</ref> or R6502), ULA and 32&nbsp;KB of dynamic RAM fitted in the Electron main unit, plus 32&nbsp;KB of static RAM, two 6522 VIA devices for interfacing, AM2910PC modem, SCN2681A [[UART]], and [[Texas Instruments LPC Speech Chips|TMS5220]] plus [[TMS6100]] for speech synthesis.<ref name="chris_bt_m2105" /> The speech synthesis was used for the "voice response" function which answered incoming voice calls by playing a synthesised message to the caller.<ref name="m2105_user_guide">{{ cite book | url=http://www.computinghistory.org.uk/det/10302/BT-Merlin-User-Guide-M2105-Messaging-Terminal/ | title=BT Merlin User Guide for M2105 Messaging Terminal | publisher=British Telecom Business Systems | date=June 1985 | volume=2 | pages=54, 78 }}</ref> The components chosen and the capabilities provided (excluding speech synthesis) are broadly similar to those featured by the [[Acorn Communicator]] which was another product of Acorn's custom systems division.

The product documentation indicates a specification with 48&nbsp;KB of RAM plus 16&nbsp;KB of "non volatile [[CMOS]] RAM" and 96&nbsp;KB of ROM,<ref name="m2105_user_guide" />{{rp|page=87}} although this particular composition of RAM is apparently contradicted by the RAM devices present on surviving M2105 machines.<ref name="chris_m2105_expansion">{{ cite web | url=http://chrisacorns.computinghistory.org.uk/Pics/BT_MerlinM2105LL.html | title=BT Merlin M2105 Expansion box circuitboard | website=Chris's Acorns | access-date=25 February 2021 }}</ref> However, the earlier Chain variant of the board does appear to provide only 16&nbsp;KB of static RAM using two HM6264LP-15 chips, also providing an extra 16&nbsp;KB of dynamic RAM using eight MK4516-15 chips, suggesting that the product evolved during development.<ref name="chain_m2105" />