MICROCOMPUTER

PURPOSE:To select and execute a specific program at low cost in accordance with the type of a microcomputer by storing previously plural independent programs to a mask ROM, and designating a program to be executed through an I/O port. CONSTITUTION:A 1-chip microcomputer 10 consists of a single IC containing a CPU11, system controller 12, ROM13, RAM14, I/O port 16 connected to an external device 15, and a clock generator 17. Plural programs are stored previously to the ROM13 according to the type of the computer. These programs are designated by the port 16, and a specific program is selected and executed in response to the type of the computer.