CGA EMULATION IMPLEMENTING METHOD

摘要

The CGA emulation method comprises the steps of; copying the content of EPROM to DRAM in different addresses with EPROM; copying the content of copied DRAM to DRAM in same address with EPROM; initializing the video register if video mode (text or graphic) has been changed; if no mode change or initializing the video register, seeting retrace time flag; copying the CGA frame buffer into video RAM if PC does not access CGA frame buffer.