Produced by Winchester Technology, this was the only Teletext board that I know of for the Nascom/Gemini systems. You will probably all be familiar with the type of graphic display that it produced - just like standard Teletext today and the (much lamented) Prestel service that we had here in the UK.
The Teletext standard, although very poor for games, is excellent for data displays on low-powered computing equipment, so it was right at home on the Nascom! WT did a very good job of integrating the standard TT chipset onto the Nasbus.
The board came with a very detailed manual covering the supplied software (Graffic), details of the Teletext graphic standard and, of course, the hardware itself.
As you can see from the above, the back cover was more than just somewhere to put a coffee cup!
There was provision on the board to connect a standard video signal from the Nascom as an input, the Teletext board having its own modulator for a colour TV. The video source could then be switched in software or by a seperately mounted switch to display either the Teletext screen or the standard Nacom text display.
As you will probably know, standard teletext display colours are red, yellow, blue, green, cyan, magenta, black " white. The Winchester Technology card played tricks with the PAL encoding of the video signal to provide six additional colours (via the modulator or combined video outputs - not the RGB output). These were maroon, purple, dark green, light blue, brown, light green and grey. These were available at the same time as the standard ones but in some cases the cursor was suppressed due to the technique used.