Abstract: The present invention discloses an automatic perimeter capable of easily adding or deleting the inspecting points.

Abstract: Disclosed is a fixed data reading system which comprises a read only memory for storing program data and fixed data, a random access memory for storing non-program data, a program counter for specifying a location of the read only memory, an incrementer for incrementing the contents of the program counter, and a program counter input register for supplying the incremented program counter contents to the program counter at a predetermined timing. The random access memory includes a data counter area for storing an address specifying a location of the read only memory in which the fixed data is stored. When the instruction for reading fixed data in the read only memory is decoded, an address is supplied from the data counter area allocated in the random access memory to the program counter. When executing an ordinary instruction, the corresponding address is supplied from the program counter input register to the program counter.