Lab 1

Basic ALU Operations: Adding Two Numbers

Learning Objectives

Understand that a CPU performs arithmetic by reading register values, passing them through the ALU, and writing the result to a destination register.
Observe the rs1_to_alu, rs2_to_alu, and alu_to_rd wires illuminating in sequence on each ADD step.

Wires to Watch

rs1_to_alurs2_to_alualu_to_rdalu_to_flags

Guided Questions

1.Step through the program one clock at a time. After the ADD instruction completes, what is the value in R3?
2.Modify the program to compute 100 − 37. Which instruction do you use? What register holds the result?
3.What is the binary representation of the ADD instruction at address 0x0002? Use the ISA table to decode each field manually.

Challenge

Extend the program to compute (10 + 25) − 8. You will need a third register and a SUB instruction. Which wires light up differently for SUB vs ADD?

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