Timed Lab 1 Arithmetic Logic Units Solution

    • Timed Lab Rules - Please Read

1.1    General Rules

    1. You are allowed to submit this timed lab starting at the moment the assignment is released, until you are checked o by your TA as you leave the recitation classroom. Gradescope submissions will remain open until 7:15 pm - but you are not allowed to submit after you leave the recitation classroom under any circumstances. Submitting or resubmitting the assignment after you leave the classroom is a violation of the honor code - doing so will automatically incur a zero on the assignment and might be referred to the O ce of Student Integrity.

    2. Make sure to give your TA your Buzzcard before beginning the Timed Lab, and to pick it up and get checked o before you leave. Students who leave the recitation classroom without getting checked o or submit after getting checked o will receive a zero.

    3. Although you may ask TAs for clari cation, you are ultimately responsible for what you submit. The information provided in this Timed Lab document takes precedence. If in doubt, please make sure to indicate any con icting information to your TAs.

    4. Resources you are allowed to use during the timed lab:

Assignment  les

Previous homework and lab submissions (this includes homework pdfs) Your mind

Blank paper for scratch work (please ask for permission from your TAs if you want to take paper from your bag during the Timed Lab)

    5. Resources you are NOT allowed to use:

The Internet (except for submissions)

Any resources that are not given in the assignment

Textbook or notes on paper or saved on your computer Email/messaging

Contact in any form with any other person besides TAs

    6. Before you start, make sure to close every application on your computer. Banned resources, if found to be open during the Timed Lab period, will be considered a violation of the Timed Lab rules.


    7. We reserve the right to monitor the classroom during the Timed Lab period using cameras, packet capture software, and other means.

1.2    Submission Rules

    1. Follow the guidelines under the Deliverables section.

    2. You are also responsible for ensuring that what you turned in is what you meant to turn in. After submitting you should be sure to download your submission into a brand new folder and test if it works. No excuses if you submit the wrong les, what you turn in is what we grade. In addition, your assignment must be turned in via Gradescope. Under no circumstances whatsoever will we accept any email submission of an assignment. Note: if you were granted an extension you will still turn in the assignment over Gradescope.

    3. Do not submit links to les. We will not grade assignments submitted this way as it is easy to change the les after the submission period ends.

1.3    Is collaboration allowed?

Absolutely NOT. No collaboration is allowed for timed labs.


    • Overview

In this timed lab, you will be creating an ALU. This ALU will take in two 8-bit inputs and one 2-bit op code. It will output one 8-bit output.

2.1    Allowed Components

When building this ALU, you may only use:

    1. basic logic gates (AND, OR, NAND, NOR, NOT),

    2. decoders,

    3. multiplexers,

    4. the built-in Circuitsim adders (NOT the built-in subtractors),

    5. splitters,

    6. wires,

    7. tunnels,

    8. constants,

    9. input pins,

    10. output pins

IMPORTANT NOTE: YOU DO NOT NEED TO BUILD THE GATES OUT OF TRANSISTORS.

PLEASE, FOR YOUR OWN SAKE, DON’T DO IT. USE THE BUILT IN GATES.

IMPORTANT NOTE: You’re allowed to use CircuitSim’s default, built-in adders (in the Arithmetic tab). So please don’t try to make your own adders, just use that one. You’re not allowed to use anything else from the Arithmetic tab (don’t try to use a subtractor; if you need a subtractor, you will need to create your own using the above-mentioned components).

IMPORTANT NOTE: Some operations will also have additional banned components. Read the instructions for individual operations carefully.


    • Instructions

3.1    CircuitSim Information

For this assignment, you will be using CircuitSim. The version is the exact same as the one used in Homework 1 and 3 and can be found on canvas under Files ! Tools ! CircuitSim ! CircuitSim.v1.jar. To ensure you are on the correct version, check to see if the title bar says "CircuitSim v1.8.1 2110 edition". If your le does not open in this version of CircuitSim you will receive a 0. All changes should be made in the timedlab1.sim le. Do not move or rename any or the input or output pins.




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3.2    ALU Components and Operation-Speci c Banned Components

You will create an 8-bit ALU with the following operations, using any of the gates listed above. All numbers should be interpreted as 2’s complement.

00.
XOR
[A ^ B]  You may NOT use the XOR under the Gates tab
01.
Multiply by 6
[6 *
A] You may only use one adder
10.
A jj B
[A || B] Note: this is a logical OR! Clari cation below
11.
Divide by 2
[A /
2]  Don’t worry about remainders

Notice that Multiply of 6, and Divide by 2 only operate on the A input. They should NOT rely on B being a particular value.

Hint: The XOR operation is equivalent to (a & ~b) | (~a & b)

Notice that opcode 10 applies a logical OR. This operation is equivalent to the following ternary expression: (A = 0 && B = 0) ? 0 : 1. That is, your circuit should output 00000000 if A and B are zero. Otherwise, it should output 00000001.

This ALU has two 8-bit inputs for A and B and one 2-bit input for OP, the op-code for the operation in the list above. It has one 8-bit output named out.

The provided autograder will check the op-codes according to the order listed above (XOR (00), Multiply by 6 (01), etc.) and thus it is important that the operations are in this exact order.


    • Checking your work

You can locally check your grade by navigating to the directory containing timedlab1.sim and running

java -jar tl01-tester.jar


    • Deliverables

Please upload the following    les onto the assignment on Gradescope:

    1. timedlab1.sim




















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