Image display apparatus

Abstract

An image display apparatus comprises: a computer unit for reading out dot data of an image pattern from a character generator and writing into a bit map type graphic memory; a CRT controller for reading out the dot data from this bit map type graphic memory and displaying on a CRT monitor; and a time sharing control circuit for time sharingly controlling the access from the computer unit to the bit map type graphic memory and the access from the CRT controller to this memory. The character generator is provided with a ROM which is constituted such that a dot matrix of one character pattern is segmented on a byte unit basis in the horizontal direction of raster and these segmented sub-patterns are continuously stored in this ROM in the vertical direction of raster. The time sharing control circuit is provided with an address selector for selecting between address signals providing access to the graphic memory in a vertical scan sequence direction from the computer unit in response to a string instruction and address signals providing access in the horizontal scan direction from the CRT controller in accordance with a predetermined time sharing control.