11.3: Muxes
- Page ID
- 26885
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When designing a CPU, muxes seem to pop up everywhere. They are the most used building block in a CPU, and most larger ICs. In the CPU presented in Figure 11.1.1, each mux is circled in blue, the following muxes are used.
- There is a mux before the $pc register to select if the next sequential instruction in the memory is to be used, or if the program should branch to a non-adjacent instruction.
- There is a mux before the ALU to select if the ALU operand will be retrieved from memory, or if the operand should be taken from the instruction itself.
- There is a mux before the $ac register that determines if the instruction is to set the value of the $ac to 0, or if the value to be stored in the $ac comes from the ALU.