Photo from 80bus.co.uk

As you can see, a large card that projected 2 inches out of the rack! This was Nascom’s biggest and best video card, with 48K of RAM on board. This could be mapped in different ways:

  • Mode 0:  The standard Nascom screen, no colour.
  • Mode 1:  (Default mode) Single density 392 x 256 pixels in 8 colours.
  • Mode 2:  Double density 784 x 256 pixels in 2 colours.
  • Mode 3:  Dual density providing 2 planes, 784 x 256 in green and 392 x 256 in blue. This allows colours blue, green, cyan & black to be used.

The colours of the three colour planes could be redefined in software (on the model B).

Unless otherwise redefined, the standard characters were:

  • Mode 0:  Standard Nascom – 48 characters per line, 16 rows.
  • Mode 1:  56 characters per row.
  • Modes 2 & 3:  112 characters per row.

Characters could be scaled in both horizontal and vertical directions.

Although this was a very capable card, it was relatively (!) low cost for such devices at the time. The video output from the Nascom was fed into this card and switched through to the output in Mode 0.

Hardware manual:  avchman       Software manual:  avcsman
Credits:  Manuals from The Nascom Home Page

AVC Model Ba


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