PURPOSE: To decrease the number of data transfer between storage devices and to improve the performance, by providing plural readout speeds possible for switching for the storage devices and reducing the types of the sotrage devices.

CONSTITUTION: Output data are transferred from a main storage device 1 to a storage deivce 5, a data group 5a to be given to an output device 6 is selected with a program among the stored data of the device 5 and the head data of the data group 5a are transferred to a register 7b. A signal generator 7d constituting a controller 7 gives a signal indicating the high speed read to the device 5 to read out the data in a high speed and is given to a comparator 7c. The comparator 7c discriminates the coincidence between the data from the device 5 with the data from the register 7b and transmits the coincidence signal to a counter 7a and the generator 7d. As a result, the data group 5a from the device 5 is applied to an output device 6 in synchronizing with the output speed of the output device 6.