The coordinate graphics unit
Abstract
The purpose of this coordinate graphics
project is to test and evaluate an unconventional
hardware design for plotting and displaying
scientific and mathematical functions. This
design project is interfaced with a 6502
microprocessor based micromputer under the
commercial name of OSl The graphics is
superimposed on alphanumeric characters of
the OSI 440 alphanumeric board.
It is a raster scan approach to graphics
which uses one byte per bright dot and does
not require memory for the dark undots on
the video display. It has been designed
to compete with the bit-per-point raster
scan approach.
The information for the dots is stored in
RAMs as 2. variable line record of horizontal
coordinates, separated by codes indicating
the end of each line.
Each horizontal record of coordinates
corresponds to a single line. The
horizontal coordinates are used to
set corresponding bit pattern into
a 256 x 1 fast bi.polar memory which
controls the video signal for the
single line. The fast memory is
loaded again for each line scan.