Abstract: An I/O circuit block comprising: a register unit; an input/output unit connected to a plurality of terminals; an instruction memory; and a state machine configured to execute a program stored in the instruction memory to transfer data between the register unit and the input/output unit. The state machine is configured to execute instructions of an instruction set, the instruction set consisting of: an IN instruction to transfer a specified number of bits into the register unit; and an OUT instruction to transfer a specified number of bits from the register unit; a JMP instruction; a WAIT instruction; a PUSH instruction; a PULL instruction; a MOV instruction; an IRQ instruction; and a SET instruction.