PURPOSE: To eliminate the need for a special circuit for skew compensation and to make the control easy, by controlling the width and interval of strobe signals at an input and output controller, in an input and output interface of a data transfer system.

CONSTITUTION: An input and output controller 2 is provided with a means which energizes the 1st control line 5 and deenergizes the control line 5 after a prescribed time, and a channel 1 is provided with a means which detects the 1st control line 5 energized and energizes/deenergizes the 2nd control line 6. The input and output controller prepares the reception of data on a data bus 4 in response to the detection of the 2nd control line 6 energized and receives the data on a data bus 6 in response to the detection of the 2nd control line deenergized. Thus, a special delay circuit for skew compensation can be eliminated.