Abstract: A work station of a computer system capable of batch storing and retrieving image data separately from a usual data file system, equipped with a main processor, main processor memory and direct memory access (DMA) controller connected to a common bus, equipped with a graphic processor and window memory between the common bus and an image data bus, and equipped with a frame memory in connection with an image display unit on the image data bus, wherein the work station is further provided with an image data memory, e.g., disk unit, on the image data bus, a memory input/output controller lcoated between the image data memory and the image data bus for controlling image data transfer using a direct memory access (DMA) function, and an image data input unit and output unit connected to the memory input/output controller, so that mass image data can be transferred directly between the memory and input/output units under control of the memory input/output controller without going through the window memory.