| 摘要 |
A computer system comprises a microcomputer and external memory means in communication with the microcomputer for storing various programs and various items of data. The microcomputer comprises a nonerasable ROM having stored therein a basic program and basic data indispensable to the operation of the system, a RAM for storing various programs or various kinds of data, a CPU for executing programs and processing data, and an interface circuit for providing communications with external devices. The external memory means has stored therein a modification program for modifying a portion of program data contained in the basic program, and a modification starting address indicating a location in the basic program where the modification of the basic program by the modification program is to be started. The CPU has an address interrupt function for processing an interrupt at a predetermined interrupt address. The microcomputer modifies the basic program by transferring the modification program from the external memory means to the RAM, storing the modification starting address in the CPU as the interrupt address, and executing a command to dump to a head address of the modification program in the RAM for an address interrupt.
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