Image processing apparatus having disk storage resembling ram memory

An processing system having a disk storage unit which acts as physical RAM storage. A disk controller, disk and small RAM unit are controlled by a separate CPU and MMU using a virtual memory scheme. This assembly is connected to a set of processing nodes by way of a bus, such that each of the nodes can access the memory directly through the MMU as virtual memory. The CPU controls the transfer of data to and from the disk as it is requested from the nodes. The nodes may then proceed to process the image data without any interaction with the host system.