CSE 140L Hardware One

Combinational Circuit Design: Full-Adder, Decoder/Encoder Circuits

Due date: Oct. 21, 1999

Objective

In this lab, we will build a half-adder, a full-adder and a 4-bit adder from the full-adder. We will also build a gray-code encoder & decoder.

Part 1. Full-adder.

i. Design a full-adder starting with a half-adder. Briefly describe the design (how a 1/2 adder works and how putting together two 1/2 adders will make up a full-adder).

ii. Use the enclosed full adder tutorial to build a full adder using xilinx program.

iii. Build a 4-bit adder using xilinx & simulate the 4-bit adder using xilinx.

iv. Demonstrate the 4-bit adder to the TA_____________________________________

Part 2. Construction of a Combinational Logic for the Gray-code ENCODER

Design a combinational logic circuit that converts three-bit binary code to three-bit gray-code (Gray Code ENCODER)

abc wxy
000 000
001 001
010 011
011 010
100 110
101 111
110 101
111 100

i.	Briefly describe what a gray-code encoder is.
ii.	Design the encoder circuit (K-map, Algebraic expression)
iii.	Build the gray-code encoder circuit & simulate the gray-code encoder using xilinx.

Part 3. Construction of a Combinational Logic for the Gray-code DECODER

wxy efg
000 000
001 001
011 010
010 011
110 100
111 101
101 110
100 111

i.	Briefly describe what a gray-code decoder is.
ii.	Design the encoder circuit (K-map, Algebraic expression, etc.)
iii.	Build the gray-code dncoder circuit & simulate the gray-code decoder using xilinx.

Report
Title page:

Names of students and due date.
Title of the lab and objective.
A brief description of each person's contribution.

Content:

Part 1 i, ii, iii, iv
Part 2 i, ii, iii
Part 3 i, ii, iii
Hint on a good report: Be descriptive but not wordy. Good example would be: Part 2.ii: The following is the design for the gray-code encoder. A bad wordy example would be: I thought about the problem for about 3 hours and realized that the best way to solve this circuit is to use the K-map and then see if we can reduce the equation even more. I solved it first and then I realized my lab partner already solved it in his notes. A no-description bad example would be : Part 2.ii Design: (with no description of what you are solving). Think of yourself as the grader but doesn't have the hand out. The grader should know what you did in the lab without looking at the hand out.

Verification:

Attach the lab assignment (this handout) at the end of the lab report with the TA verification.

Grading

90% will based on the completeness and correctness of the report. 10% will based on the neatness, organization, and following instruction of the report format.

i.	Design a full-adder starting with a half-adder. Briefly describe the design (how a 1/2 adder works and how putting together two 1/2 adders will make up a full-adder).
ii.	Use the enclosed full adder tutorial to build a full adder using xilinx program.
iii.	Build a 4-bit adder using xilinx & simulate the 4-bit adder using xilinx.
iv.	Demonstrate the 4-bit adder to the TA_____________________________________