| Control unit | ||||||||||||||
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| New features: | Fig. 5.17 | |||||||||||||
| Instruction bit numbers for register numbers, opcode, function | ||||||||||||||
| MUX to select destination register | ||||||||||||||
| RegDst: selects $rd or $rt to write data | ||||||||||||||
| ALU control: uses function code and ALUOp to generate ALU operation selection | ||||||||||||||
| What is ALUOp? 2-bit code generated by main control (stay tuned) | ||||||||||||||
| Note that the values of RegDst, ALUSrc, and PCSrc are reversed in this diagram. | ||||||||||||||
| The version in the current printing of the text is correct. | ||||||||||||||