Apparatus for storing and accessing image data to be displayed on a

Abstract

A memory storage and accessing device is constituted by a plurality of plane memories. Memory elements are arranged in each plane memory two-dimensionally, and a plurality of image data are stored in a word direction in each plane memory. In addition, plural plane memories are disposed in a pixel direction. Hence, plural image data are stored two-dimensionally in word and pixel directions. The memory device is constituted such that a port connected by a word data bus and another port connected by a pixel data bus are provided therein. Due to these two ports, it is possible to perform an independent access so as to independently read out and write in word data and pixel data. The memory storage and accessing device is capable of masking bits of data and memory units, using both static and dynamic masks. In the static mask, mask data are applied all at once in one memory cycle, or the mask data are supplied to the memory device at plural times in one memory cycle. In the dynamic mask, the mask data are supplied to the memory device at plural times in one memory cycle and the mask positions can be sequentially changed. The memory storage and accessing device of the present invention is also capable of comparing pixel and word data with compare data in each plane memory and in combination with a masking operation.