CIS 351

Project 1: Build a Signed Adder

Fall 2018

Due: Monday, 17 September 2018

For this project, you will use JLS to implement a signed adder.

Pre-requisites

The "Intro to JLS" lab provides an introduction to using JLS that you may find useful. This lab also explains how to obtain, set up, and use JLS, as well as use the DLUnit testing software. It is not due for credit.

This video demonstrates several helpful JLS shortcuts. Remember, JLS was designed specifically with these projects in mind. If you find a task highly repetitive/tedious, you are probably overlooking a shortcut.

Task

Implement a 16-bit signed adder using any algorithm you wish, provided the circuit has a reasonable running time and size. Faster adders will receive more points. (See Grading section below.) Your adder must report overflow conditions when they occur (with respect to signed inputs). Notice that this circuit must have an input named CarryIn. You will use this input for future projects.

Your inputs must be named InputA, InputB, and CarryIn. If not, your circuit won't work with my tests.

Your outputs must be named Output, CarryOut, and Overflow. CarryOut is the carry out from the last full adder. It is also, in effect, the overflow indicator for unsigned inputs. Overflow is the overflow indicator for signed inputs. Remember, CarryOut and Overflow will not necessarily have the same value.

You may use SampleSigned16BitAdderTest.java as a basis for your own tests. Warning! This test file is incomplete. Don't assume that a circuit that passes this sample test will pass all of my tests.

Rules

You are strongly encouraged to work in groups of two. You may work alone only with permission of the instructor.
The simulator comes with a built-in adder. You may not use the built-in adder.
To build the required circuits, you will probably find it useful to design and build several subcircuits. These subcircuits may have any interface you choose; however, you are responsible for testing them.
You must write all of your own chips. In other words, you may not share "internal" chips with your classmates, or download them off the Internet.
Be sure to test your components thoroughly. Just because it passes the test included here doesn't mean it will pass my test.

Hints and shortcuts

Remember, JLS inserts the code for sub-circuits directly into the circuits into which they are imported. Thus, changes to sub-circuits are not seen by the circuits that contain them. If you discover a bug in a sub-circuit, you must delete and re-import that sub-circuit into the parent. (Again, test your subcircuits thoroughly before importing them!)
Remember that no software is perfect. This includes JLS and JLSCircuitTester. It is in your best interest to start early in case problems arise. Also, please e-mail me with any bugs you find or feature requests you have. If JLS crashes, please e-mail me the JLSerror file.

Grading

This assignment will be scored out of 100 points.

Category	Rubric	Maximum Score
Functionality
	Not attempted	0
	Substantially complete, but passes no tests	15
	Passes a few tests	25
	Correctly adds positive integers only	45
	Correctly adds positive and negative integers (but overflow does not work correctly)	55
	Passes all tests	65

Date 100% correct
	Two days early	12
	One day early	11
	On time	10
	One day late	8
	(-2 per day)	...
	Five or more days late	0
Date `output` correct
	On time	10
	One day late	8
	(-2 per day)	...
	Five or more days late	0
Speed
	≤ 75	9
	≤ 125	8
	≤ 175	7
	≤ 225	6
	≤ 275	5
	≤ 300	3
	> 300	0
Presentation
	Size and Speed^*	5

^*For 5 points, correctly specify the exact number of gates used by your adder (the total number of gates, including all sub-circuits) and the time required by your adder (i.e., the sum of all the gate delays along the critical path).

Penalties

You will loose 3 points for each buggy submission (-5 if the submission contains too few tests).
You will loose points if your circuits are not neat and well-documented.

Deliverables

To submit your project:

Add a text box to your jls files that includes
- your name,
- the file name,
- the assignment name, and
- the assignment due date.
Your adder should also include a label indicating time and gate count. The time should be the maximum simulation needed for any addition. (I'm looking for an actual number, not a big-O expression.)
Either
- Attach all relevant .jls files, bug reports, and test classes using Assignment Manager. (Attaching your test classes allows me to determine how well you tested your code, and assess partial credit if necessary.)
- Add me (kurmasz) as a collaborator to your GitHub or BitBucket project and ask me to pull your code. (Your repository must be private / inaccessible to other students.)