PURPOSE: To realize the facsimile equipment in which lots of functions are given to the user with a small capacity and inexpensive ROM by decoding a program written in the ROM with compression and writing the decoded program onto a RAM and operating the facsimile equipment according to the program on the ROM.

CONSTITUTION: A program built in a ROM(A)2, a ROM(B)3 is written properly in a RAM(A)4, a RAM(B) 5 and a CPU 1 executes various functions of the equipment based thereon. Then a basic program is written in the ROM 2 and other program is compressed and written in the ROM 3, the RAM 4 corresponds to the system RAM and the RAM 5 corresponds to the ROM 3. In this case, the program required for the selected function is expanded in the RAM 5 and the program corresponding to the function not selected is deleted from the RAM 5 to save the capacity of the RAM 3 and the RAM 5 is used effectively.