io-unknown

This board was a stunner at the time! (The example shown in the picture is incomplete, not working and a little worse for wear!)
Facilities offered were:

  • Video processor IC with 16k of dedicated on-board RAM
  • Two sound generator ICs with 3 channels each
  • Eight analogue inputs
  • Battery-driven real time clock (choice of 2 ICs)
  • 2k of battery-maintained CMOS RAM
  • Counter-timer IC
  • Everything mapped into the Z80 I/O space – uses no RAM

If you wanted to write games, this was the board to do it with!

The video processor on the board in the picture is the TMS 9928 (although a Nascom Newsletter review says it was the 9929). This was a close relative of the 9918 which was used in the MSX computers amongst others. At the time (late 1982 / early 1983) this was an extremely impressive device:
Screen resolution of 256 x 192 with 16 colours
32 sprite planes
Sprite planes can be layered to move one sprite in front of another
Up to thirty-two 8×8, 16×16 or 32×32 sprites
Sprite collision detection built in
Sprite magnification changeable under software control

The board’s major failing was that the video output was not suitable for direct connection to a TV or colour monitor.

Software supplied with the board was on a cassette tape and written in Pascal so that board access procedures could be copied easily by the user.

Peter Smith kindly contacted me after seeing my plea for information on this board and I can now pass some of it on to you! Firstly, there were two manuals supplied with it:

agc-scagc-mc
I have only shown the covers on this site as the content is rather large in comparison with the possible interest in this particular item!
The workings of the board were originally described in Radio and Electronics World in a January 1983 article by S.J. Holmes, the hardware designer.