11.4: Adder
- Page ID
- 26886
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The ALU is the part of the CPU that implements operations, such as add, subtract, multiply, divide, OR, AND, shift, etc. The adder in this text was presented as an exemplar of an operation which would be done in the ALU. In this ALU, there is an ALUOpt control bus that consists of 4 wires, which can specify up to 16 operations. Only 4 operations are implemented in this ALU, integer add, sub, multiply, and divide. All 4 operations are calculated all the time, but only one result is ever returned, and that result is selected by an ever ubiquitous mux.
