Formation and transmission of a dynamic graphics display

Abstract

The NEC 7220 / GDC is a high resolution colour graphics display controller. It is programmable, and can generate lines, arcs and rectangles at high speeds with little intervention from the host computer. The GDC has interesting capabilities such as scrolling, DMA transfers and read and write of its display memory through the FIFO buffer. This thesis describes the GDC and its relation to the other components of a graphics terminal. Software programs are developed and implemented to show how the GDC's capabilities can be used to generate a dynamic graphics picture on the CRT screen. The programs are written in both Pascal and 8086 assembler. Two methods are presented for the transfer of a graphical display from one NEC/APC to another one. The first technique sends the display memory's pixels and the second one transfers the picture codes for the reconstruction of the image. For each of them software programs are developed and tested thoroughly and found to perform as stipulated.