PURPOSE: To use one entry to process a command having plural operands by using one entry of an operand storage table independently of the number of operands and performing first and error check.

CONSTITUTION: All operands are read from a storage area of a display control program of a computer 3 by the start of an application program while performing the error check. The number of operands is set to a table counter, and the operand storage table is cleared to 0, and contents of the table counter are checked, and the processing is terminated if they are 0. If they are not 0, one operand is taken out from the operand storage area into the operand storage table. A designated file is taken out from a microdisc 1 in accordance with contents of the storage table and is written on a floppy disc 2 or the reverse processing is performed. The operand storage table is logged out, and the table counter is counted down by one, and the operand storage area is counted up.