PURPOSE: To perform an interruption processing at high speed, by providing a specific one-byte instruction code when the interruption processing is performed on a control means, and an ordinary processing is stopped, and a processing is jumped to another address.

CONSTITUTION: A microprocessor 1 reads out a code from a memory 2. As a various kinds of instruction codes stored in a memory 2, there are a one-byte instruction which requires no address data, and a two-byte instruction, or a three-byte instruction which requires the address data. The microprocessor 1 judges while byte instruction code is the instruction code, and identifies which code is an instruction code, and which code is a data code, in order. As a result, it is resulted that a jump processing by a conventional three-byte instruction can be realized by the specific one-byte instruction code, and processing speed by the interruption on the processor 1 can be remarkably improved.