easier to use. The present generation of computers is much more
‘user friendly’, enabling almost anyone to become a computer
user. This continuing improvement in the man-machine (person-machine?)
interface can only serve to widen the acceptance of
computers in everyday life.
The advent of the personal computer has made it possible for
problems to be solved which would previously have been
prohibitively expensive to solve by means of computers.
However, the cost of computing is not the only obstacle to
acceptance of computers, particularly in the area of the person-machine
The solutions to the person-computer interface problem are now
becoming more readily available – colour graphics and speech
being areas which offer the most promise. Speech simulation is
already available for the Nascom range of computers, although
reliable speech recognition is still some way off. The ability
to communicate to the computer user complex or simple results
has always been a problem in the past, but now that high-quality
colour graphics displays are available this hurdle can be
Colour graphics enables the computer to present information
pictorially, which greatly improves the usability of programs.
Sometimes information is difficult or impossible to present
using only numbers and words, but becomes easily comprehensible
in graphics form. Even computer output which does not require
colour graphics to be usable will usually become clearer when
converted to colour. The use of high-quality colour graphics is
now open to all users, enabling business, scientific,
engineering and other users to gain maximum efficiency.
The addition of quality colour graphics to the Nascom range of
computers is achieved by means of the Advanced Video Controller
Equally important to the effective implementation of
colour graphics is comprehensive and easy to use support
software, and this is provided as standard with the AVC. Access
to the colour graphics is made simple from either ROM BASIC or
Extended BASIC (XBASIC), the latter being available for tape,
NAS-DOS and CP/M users.
The principles of displaying a graphics picture are transparent
to the user, but to gain a better understanding an insight into
the theory of graphics in general will be useful.
The AVC works on the bit mapped raster which scan principle, which
means that the computer can directly access and set the colour
of any graphics point (known as pixel) on the display. This
provides a much more flexible system than that allowed with a
programmable character generator system. While programmable
character generator (PCG) systems can offer faster graphics
generation of a limited range of character shapes, they suffer
severely from programming difficulties and the lack of
generality of the pictures that they can represent. Normally
they are limited to only 128, or possibly 256, special