HIGH-SPEED HORIZONTAL LINE PLOTTING CONTROL SYSTEM

PURPOSE:To speed up horizontal line plotting by discriminating between horizontal lines and non-horizontal lines in straight line plotting and using the high- speed access mode of a dynamic RAM by utilizing the feature that plotting addresses succeed in the case of a horizontal line. CONSTITUTION:A CPU 1 judges whether a segment to be plotted is a horizontal line or not, generates a mode signal indicating the result, and sends a request to a display memory 7 together with the mode signal. An arbitor part 2 determines the internal operation of a CRT display device according to the address decoding result of a decoder part 3 and the horizontal line judgement result of the CPU 1 and inputs the determined internal operation result to a memory control part 4. The memory control part 4 generates faster plotting cycle timing than plotting to random addresses when plotting to successive addresses continues and performs plotting on a display memory.