PURPOSE: To provide a field programmable gate array with a private route directly connecting a selected register within a programmable function unit array and an I/O pad. CONSTITUTION: The gate array is provided with the private route 508 directly connecting the selected register 503 within the array of the programmable function unit 501 and the I/O pad 512. For example, the direct connection, namely connection without through a configurable mutual connection point, to the selected register within PFU given from the I/O pad through an input driver is realized and this same route or a different route is used for directly connecting a register output from given PFU to the I/O pad through an output driver 507. The necessity of a special I/O register in a programmable input/ output cell is avoided to make EPGA design flexible and to facilitate designing. COPYRIGHT: (C)1994,JPO