Display control circuit including hardware elements for preventing undesired display within the display space of the display unit

摘要

For display control of a liquid crystal display, display data and address signals for designating display dots are required. Segment address data designating X-direction addresses in the display space and common address data designating Y-direction addresses are input. Processing such as block transfer of address data in cases where the display address extends beyond the display space and where display picture is shifted within the display space has hitherto been carried out by software, but this places limitations on display speed. In the present application, the display space is divided in the X direction and the divisions of the display space are separately served by phural segment drive circuits. A common drive circuit is provided with hardware elements for selecting individual segment drive circuits so as to match the display address. This permits high-speed display operation and facilitates provision of software regulating the operation CPU.