TODO: By analogy to the last circuit from Section 3, describe how thealuA,aluB, andfunctioninputs determine the value ofvalE– what does this value represent?TODO: By analogy to the last circuit from Section 3, describe how thealuA,aluB, andfunctioninputs determine the value ofvalO– what does this value represent?
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Further Analysis
The Concise Y86 ALU only has the functions to add, subtract, AND, and XOR.
TODO (further analysis): By
making use of the relationships between multiplication/division and addition/subtraction, how could
the Y86 ALU be used in a larger circuit to multiply numbers or divide numbers? Are there any values
that it cannot evaluate? Why or why not?
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End of Lab Survey
TODO: To help us improve these labs both this term and for future offerings, complete the survey at
.
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Magic Box cleanup
TODO: Before leaving the lab, show your Magic Box to your TA.
A
Marking scheme
All labs are out of ten marks, with two marks for pre-labs, and eight marks for in-lab work. In more detail:
•
Two marks - Pre-lab questions
•
Five marks - In-lab questions. In this lab, it is one mark for the demltiplexer implementation, one mark for the
mux-demux scheme, one mark for the multiplexing circuit, and two marks for the concise ALU questions.
•
One mark - Further analysis.
•
One mark - End of lab survey.
•
One mark - Magic Box cleanup.
TAs may at their discretion award one bonus mark, such as for completing the challenge problem.
B
Challenge Problem
Addition is a basic operation in many ALUs. Using only basic logic gates (ie. AND, OR, XOR, NAND), design a circuit that
takes two two-bit binary numbers and produces their sum. The circuit must be able to output the sum
11 + 11
correctly.
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