Low resolution graphics – 391 by 256 points with one of eight
colours per pixel.
High resolution graphics display giving a resolution of 784 by
256 with one of two colours per pixel (on/off monochrome)
Mixed density graphics display giving resolutions of 391 by 256
and 784 by 254 combined, with each pixel having one of four
Mixed text and graphics – the Nascom 2 video RAM output
combined with one of the graphics displays.
This command specifies the colour to be used in succeeding commands.
In addition to just specifying a single colour (one of the eight
already mentioned) the
allows the use of special shading
colours which can be used to differentiate areas such as graphs or
shadows in pictures. These shading colours are specified to the
computer as the relative levels of the three primary components of
colour (red, green and blue), allowing a selection of 4913 different
This allows the whole of the display to be set to a specified colour
in a background colour. Again up to 4913 colours are available.
This is a special command that sets up all the default values of the
This command is used to specify the centre of rotation to be used in
those commands which allow a rotation to be specified.
This command has two functions – to select the combination of
primary colours which are available for drawing purposes (as
distinct from MODE, which determines which colours will be displayed
after shapes are drawn) and to specify how the shapes are to
drawn. This last parameter is rather difficult to explain – shapes
can be drawn as they would be with coloured pens on paper, but they
can also be draw in other ways. These other ways produce effects
which change the shapes appearance and colour. The effects are
similar to television visual effects.
This command instructs the computer which parts of the display can
be used for the output of graphics or text. It can be used to
protect areas of the screen so that they cannot be over-written.
This command allows the picture which would normally be displayed on
the screen to be output to a matrix printer with dot graphics
This allows the user to save the current display picture on disc.