JPS5785162A - Picture memory access control system - Google Patents

Abstract

PURPOSE:To execute the access to a picture memory at a high speed, by updating a value of a register in accordance with an output signal of a zero-checking circuit, continuously adding ''1'' to this value, and generating a memory address in order. CONSTITUTION:A picture memory access control device 3 is started by a picture memory access request 8, outputs a control signal 50 by use of an X zero signal 27 and a Y zero signal 31, and executes an access control to a partial picture being in a picture memory device 1. In case the partial picture is accessed in the lateral direction, a register D and a register F are set to a register E and a register G, respectively. Subsequently, +1 is repeated, updating a register A, an address is generated in order, and the memory is accessed. When an E-counter is subtracted by synchronizing with said operations, E becomes zero, and the X zero signal rises. By this X zero signal, B+C of registers are executed and its output is set to both A and B. Subsequently, D is set to E, and subtraction of a G-counter is executed. When it is repeated, both the signal 27 and the signal 31 rise at the same time, and the access to the partial access picture is finished.