Dr Paul Johnson had studied digital audio and television electronics at University and was working for a firm called Cambridge Consultants - the same Cambridge Consultants which designed what became the Dragon32. In his spare time he started another company called Tangerine with a former schoolfriend, this company sold a kit board called the Tangerine 1648 to allow a normal television to be used as a computer terminal. The 1648 name came from the amount of text on screen - 16 lines by 48 columns. Johnson then started developing a computer which would use a tv as its display, and with support from Barry Muncaster (also at Cambridge Consultants) he set up a new company named Tangerine Computer Systems in October 1979. Spot the fruit theme, it was all the rage at the time for some reason.

Development of the machine was soon completed and it became one of the world's first kits based around the fairly new MOS 6502 CPU. It was named the Microtan 65, from 'Micro'computer and 'Tan'gerine with '65' because of the CPU. Launching in December 1979 at £75 for the simplest kit, it consisted of just a PCB and a 20 key hex keypad. Everything you needed was present though, including the TV output and a 1K Monitor ROM for you to enter and edit programs in assembler. The machine was an immediate success and Dr Johnson left Cambridge Consultants in Jan 1980 to concentrate fully on Tangerine.

The TANEX board soon followed the Microtan. This connected to the CPU board via a simple 2-slot backplane and contained 7K extra RAM, 14K of EPROM space and a much needed cassette interface for loading and saving from tape. Two serial interfaces were also provided via a pair of 6522 VIA chips. The 6522 ('Versatile Interface Adapter') had been invented by Chuck Peddle of MOS Technologies a few years earlier, and became the mainstay of machines like the Commodore PET, Vic20, C64, Victor 9000 (which had 6) and even the Apple Lisa.

Whilst the basic kit was very limited it was designed to be expanded from the get go. The user manual states "Unlike most other microcomputers, microtan 65 has been designed from the start with a small system in mind, therefore expansion of the microtan 65 is a concept, not an afterthought."

This meant the machine was potentially much more capable than other early computers such as the Science of Cambridge MK14 and Acorn System One. Sinclair launched the ZX80 not long afterwards, a much more usable machine straight out of the box since it included a full keyboard, of sorts, and spoke BASIC. However, It had very limited expansion potential and perhaps wasn't aimed at the same market.

(the market for the ZX80 was me - I wouldn't have known what to do with a Microtan.)

The software side of Tangerine was presented as Tansoft, who produced programs and a regular newsletter called the Tansoft Gazette which followed the form of other machine-based newsletters of the time - product news, software snippets, errata, embarrassing pictures of the staff etc.

Over the life of the machine several add-on cards were produced from RAM expansions to ROM boards (early solid state storage), hi-res graphics, colour graphics, floppy controllers and more. The interest around the machine was sufficient for its own user group to be created - the Tangerine Users Group or TUG. TUG produced its own newsletters as well as a fully usergroup designed expansion board called the TUG E.S.C - EPROM Storage Card. This board contained sockets for up to 16 EPROMs and worked via a host EPROM in the TANEX expansion. Using the control program in the host you could copy a whole segment of EPROM into main RAM and run it, meaning that at powerup you had a whole host of available apps to choose from.

The periodical magazine Electronics Today International (ETI) also produced articles and expansion boards for the Microtan, these included a sound board, real time clock and an EPROM programmer. With TUG they also produced software, the best example of which is probably the aforementioned Space Invaders. It's a very splendid version and inspired ETI to design a board around a Microtan65 to which wou added buttons to make a fully discrete Space Invaders game you just plugged into a TV. A couple of manufacturers produced these for sale.

The rise of the Prestel Viewdata in the UK inspired Dr Johnson to design a teletext adapter that also plugged into a TV, and was also based on the Microtan. Known as the Tantel, it was the beginning of a whole range of viewdata terminals from another spun-off company called Tandata. That's another story though.

Tangerine sold the Microtan buiness to a company newly renamed Microtanic Computer Systems in 1983 who continued producing boards and supporting the machine. Meanwhile, Tangerine themselves morphed into a new company called Oric Products International. You may have heard of the machine they produced :)

Microtan 65 in a lovely home-made wooden box, donated by Dave Maddocks. Thanks!
Microtan 65 with 7 slot backplane from Kevan Heydon :)
Oric-1 boxed complete with all the bits and bobs.
Slightly different Oric-1 with Multicolour label.
Oric Atmos with large Cumana interface and even larger dual floppy drive, from Peter Wooley.
Oric Atmos 48 with Intro Tape and Manual.....nice keyboard!
Oric MCP40 Colour Printer, mint, unused. The pens are still in their tubes and the paper's still wrapped.
Loads of software and some books for the Orics

An excellent history of Oric Products International and the products it produced can be found here