The 6845 Cathode Ray Tube Controller (CRTC) is a programmable IC used to generate video displays. This IC is used in a variety of computers including the Amstrad CPC, Amstrad CPC+ and KC Compact.
The CRTC is a simple chip really . It is just a bunch made up of counters and equality operators, tied by simple logic. But All the devil is in the details, and that's what we will discuss in this articlecomplexity stems from its multiple independent implementations with their subtle differences.
The CRTC was a common part available from many different manufacturers. During the life of the CPC, Amstrad sourced the CRTC from various manufacturers.