Data Registers: 暂存ALU的计算结果
Instruction Registers: 存储当前正在执行的指令
Program Counter: 下一条指令的地址
Address Registers: 存储当前指令所访问数据的地址
Control and Status Registers: can store both data and addresses, i.e., they are combined Data/Address registers.
Program Status Word: 程序状态。如进位标志、溢出标志、中断状态等