JPS6430364A - Area designation circuit - Google Patents

Abstract

PURPOSE:To simplify the hardwares by controlling a sequence control at the time of write but the control of only video line clock at the time of read and separating an address into a division for main scanning direction switching and a subscanning direction switching. CONSTITUTION:At the time of writing in a memory 11 to store the main- scanning-direction address of an area-switching point as data, both the data and the address are controlled in accordance with a sequence, hence an interruption can be executed independently of the clock for video and line, but at the time of reading, the control is achieved only with a video line clock. Also, the address is divided into two divisions; one is for a main-scanning direction switching and the other for subscanning direction switching, and at the time of writing, subscanning direction information is added in order that a function to process both read data and video data in real time. In such a way, the read and write from and in the memory 111 can be completely separated into the sequence-control and the hardware control by a clock, therefore, one memory can be used in common for a write and a read. As a result, the constitution of the hardwares in the vicinity of the memory can be simplified.