Tandata td2500

I recently picked up a Tandata td2500 at a London, UK car boot sale. Does anybody know what it is? It is basically a keyboard with outputs on the back for TV video, composite video, RGB (SCART), serial data, and a lead to plug into a telephone outlet. The power supply is missing and plugs into a 4 pin DIN plug - any info on voltages to use to power it up. The unit was made by Tandata UK Ltd. Also I like to hear what's available to buy - so here is a non-US version of what I picked up at a large South London car boot sale on Saturday. Epson PX-4 + cartridges (works) - 5 pounds (L) (1 pound = 1.6 $US) 2 x BBC model B (both work) - 1 L each Casio pocket computer PB-410F (no battery) - 5 L EG 2000 Colour Genie (works) - 3 L NCR PC4i - nice all-in-one unit but turned out to be IBM XT clone - 5 L old Sharp calculator - 1 L Vincent Murray Email v.murray(a)unsw.edu.au