PURPOSE: To improve program performance by decreasing the frequency of a block input/output process which is generated when a block expanded on an external storage device is accessed.
CONSTITUTION: In addition to blocks A and B stored in a basic memory 2, the external storage device 3 is stored with blocks C-E exceeding the capacity of the basic memory 2, A block management table 1 is used to manage the storage positions and update states of the blocks. When the block B in the basic memory 2 and the block C on the external storage device 3 are swapped, the block management table 1 of the block B is referred to and when the block B is not updated, the block C is read in the basic memory 2, but when the block B is not updated, the block C is read in the basic memory 2 after the block B is saved on the external storage device 3.
YAMAMITSU TADASHI