DATA TRANSFER DEVICE

PURPOSE:To transfer data in 8Xn-bit units in the microprocessor side by providing prescribed interface circuits for the first and the second data busses between the microprocessor and a peripheral device. CONSTITUTION:When 16-bit data is outputted to the first data bus 12 from the microprocessor after the first control signal -WR1 of an interface circuit 15 is made active by the microprocessor, this 16-bit data is written in the first register 17 through the first bus interface circuit 19 in the interface circuit 15. In response to this write, the peripheral device side makes the second control signal -RD2 of the interface circuit 15 active and reads contents of the register 17, 8 bits by 8 bits. The microprocessor reads data from a register 17 similarly.