Page printer controller

DETAILED DESCRIPTION An object of the invention is to improve the page printer controller's processing time by increasing the controller's processing speed while concurrently operating the respective processors.
The above object can be achieved by the provision of a page printer controller having a compressed image data expanding function and a graphic function including a function of enlarging and reducing the expanded image data, said page printer controller, comprising: an expanding processor for expanding image data in a compressed data format sent from a host apparatus and restoring the expanded image data to image data in a dot pattern format; a memory for temporarily storing the image data restored in the dot pattern format by said expanding processor; a graphic processor for reading the image data in the dot pattern format in the memory and graphically processing the read image data; and a memory access arbitration circuit for concurrently operating both processors.
When the expanding processor and the graphic processor are operated concurrently, the problem that the two processors scramble to access the commonly used expanded image memory is addressed.
The memory access arbitration circuit is so designed as to mediate access to the expanded image memory between the expanding processor and the graphic processor, so that the two processors can operate concurrently in an efficient manner.