Abstract operation-signalling from a raster scan video controller to a display memory.

摘要

A generalized operation-signalling logic for a raster scan video controller whereby the video controller, in accessing the memory of a computer system, can indicate what type of operation is to be performed at each memory address to be accessed. The signalling scheme provides a rich set of functions, logic to generate this signalling and an external PLA-type device which interprets this signalling for a wide variety of memory types.