General purpose display controller

This is a simple display controller. It can be controlled with a small microcontroller, such as MCS51, 68HC11, Z80, AVR and others.However, it is not suitable for practical use because the microcontroller is occupied in synthesizing video signal, it cannot process any other operation. The CPLD used for main controller is XC95108(PLCC). It has 108 macrocells and 69 I/O port(some have gloval function), so that it is just suitable for this project.Most function is integrated into the XC95108, therefore, number of parts and wires could be reduced. The CRTC block is counter array to generate display timing. The timing controller block is the main logic to arbitrate between host access and display access to the video buffer