Display range control apparatus and external storage unit for use therewith.

摘要

A display range control apparatus includes an external storage unit in which position data representative of two points in a horizontal direction on a screen of a raster scan monitor are stored in advance together with a still picture pattern data and character data. A counter is incremented for each dot or pixel on the screen. In a range where each of the position data is coincident with a count value of the counter, a masking signal is obtained. The masking signal is used for gating picture data, by a gate circuit. The picture data which outputted from the gate circuit is converted into a video signal which is then applied to the monitor.