Questions about the Motorola MC6845 CRT Controller chip, or clones of it (e.g. MOS 6545).
The MC6845 was a timing and memory address generation controller chip for producing CRT displays, intended originally for text mode displays, but also used in various machines for producing graphical raster displays also. There were clones produced by several manufacturers including MOS Technlogies and Rockwell (referred to as 6545 in this case). It was used in many computers, including the Commodore PET, BBC Micro, Amstrad CPC464, and in the MDA, CGA and EGA video cards for the IBM PC.