| 摘要 |
A microcomputer device contains a CPU with an arithmetic/logic unit and data/address registers on a single semiconductor integrated circuit having a combined on - chip read/write memory for macrocode and microcode storage. A macrocode word is fetched from the memory and stored in an instruction register in the CPU, then a sequence of microcode words is fetched from the same memory based on this macrocode word. Both macrocode and microcode may be loaded into the combined memory from external to the chip, so the functions of the microcomputer may be changed for different tasks. The content of both microcode and macrocode, as well as the ratio of macrocode to microcode, can be varied by programming without any change in the circuitry of the chip.
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