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M4000

The BT Merlin M4000 is a very obscure computer from the mid 1980s. It is allegedly based on the Logica Kennett, and should not be confused with the BT Merlin Tonto which is a rebadged ICL OPD.

The exact application of M4000 is unknown, but it was almost certainly developed for internal use by BT and never sold on the open market. It could have been used in conjunction with System X telephone exchanges.

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Contributors: Riaz Sobrany

Stevie Skellett (UK) reports:
These machines were certainly used outside of BT. The Royal Navy used them for admin tasks in the 80's. The machine I used had a 3.5" 720K floppy drive and a 20MB 'Winchester' hard disk. The OS was Concurrent DOS if I remember right. You could have 4 virtual terminals selected from a keyboard key. We had a vastly underrated, if not very user friendly, WP package called Lex9b. Once you learnt all its tricks, many of which did not figure in our user documentation, you could really make it sing. Mine also had another, similar sized, unit containing the Tape Backup Drive - backups took a *long* time!

Ray Chester adds:
The DSS used these computers. Installed and maintained by BT Merlin. The systems were built for specific functions for example "Social Fund" had a couple of units with Social fund software and a Dot matricx printer. These machines would keel over from any passing static charge. They also had the Asteroids game written for them lol

Col comments:
My introduction to IT. I worked on these for 5 years or so. These were used extensively outside BT. Major government contracts (as above post mentions), used by the armed forces and small companies such as solicitors etc. Also used by most of the theatres in the UK, using a box office app called RITA. They ran bespoke software apps and also had a word processor app called "Merlinword". Other variants had single floppy and 10 or 20meg hard drive. Also an 80meg hard drive or a Tandberg tape drive in its own casing. The RITA system even networked these together, using ARCNET. The nodes were addressed by using jumpers on a network daughter board. Oh happy days !