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上一讲已经介绍了CPU内部的寄存器,这一讲和下一讲将在此基础上学习Z-80的指令系统。Z-80 CPU可执行158种指令,其中包括8080A的全部指令78种。一条指令包括两部份内容,一是给出操作码,指出进行何种操作,另一个是给出操作数,它可以是操作数本身、操作数所在的寄存器名字或内存单元地址。Z-80指令种类较多,全部指令不可能都用单字节来编码,除了单字节指令外(这是主要的),还有双字
Previous lecture has introduced the internal CPU registers, this talk and the next lecture will be based on the learning Z-80 command system. The Z-80 CPU can execute 158 commands, including 78 commands for all 8080A’s. An instruction consists of two parts, one is given the opcode, which indicates what kind of operation, and the other is given the operand, it can be the operand itself, the operand where the register name or memory unit address. There are many types of Z-80 instructions, all of which can not be single-byte encoded, except for single-byte instructions (which is major) and double words