PURPOSE: To easily use a floppy disk even in its use outside view area, to make it to a cassette type so as to be freely attachable and detachable, and to carry and replace it easily, by constituting so that a bubble memory can be directly connected to a floppy disk controller.

CONSTITUTION: An output of a floppy disk driver (FEE) 1 is transferred to a write exclusive floppy disk controller (FDC) 9 and a read exclusive floppy disk controller (FDC) 10 through a separating circuit 8, and these FDC 9 and FDC 10 send and receive data to and from a data buffer DA1. A system controller 13 sends and receives data to and from a bubble memory controller 18 through a data buffer DA3. An address write exclusive floppy disk controller 11 sends and receives to and from a standard memory SMO2, a system controller 17 and an input/output device 15 through a data buffer DA2.