A system capable of efficiently transferring a command set for controlling an image forming apparatus to the image forming apparatus from a host apparatus. A command separate/storage unit separates an image forming command set into a context command set and an object command set, and allocates both command sets in a main memory device. A command read instruction transmission unit transmits a command read instruction having a transfer size and a storage address of each of the allocated context command set and object command set, to the memory access controller. The memory access controller compares the storage address of the context command set included in the received command read instruction with a previous storage address, and reads the context command set from the main memory device only when both storage addresses differ from each other.