HOME TASK 1
HOME TASK 1
Part 1 -
Create the digital circuit for the following logical expressions using Logisim and answer the following questions.
The digital circuit has 2 inputs, D and E, and 2 outputs, Q and Q'.
Q = (D NAND E) NAND Q'
Q' = ((D NAND E) NAND E) NAND Q
a) How does this circuit work?
b) What does this circuit resemble?
c) Explain, step by step, what happens in the following scenario:
- When Q' = 1, set Q' = 0.
- Then, set E = 0.
- Later, set D = 0.
- What happens when E is later on set to 1?
d) Simulate the previous scenario and send a screenshot of the result.
Part 2 -
Create the following digital circuit using Logisim and answer the following questions.
Do not try to simplify the provided logical expression as the simplified version may create oscillations and leads to incorrect results.
You are expected to observe the functionality of the newly added unit. You are required to use the circuit you have created in Part 1 for this part.
You should study the Subcircuits tutorial for Logisim from this link to get yourself familiarized with creating and using subcircuits: http://www.cburch.com/logisim/docs/2.7/en/html/guide/subcirc/index.html
The digital circuit has 2 inputs, C and D, and 2 outputs, Q and Q'.
The D input in the circuit in Part 1 should be directly connected to the D input of this circuit.
The E input in the circuit in Part 1 should be connected to the C input of this circuit satisfying the following expression:
E = C AND (NOT (NOT (NOT C)))
The Q output in the circuit in Part 1 should be directly connected to the Q output of this circuit.
The Q’ output in the circuit in Part 1 should be directly connected to the Q’ output of this circuit.
a) What does the added unit do?
b) What does this circuit resemble?
c) What can be done with this circuit?
d) Explain, step by step, what happens in the following scenario:
- When Q' = 1, set Q' = 0.
- Then, set C = 0.
- Later, set D = 0.
- What happens when C is later on set to 1?
- While C is still 1, set D = 1. What is observed at the output in this case? What is the reason for the corresponding output? If this step were conducted at the end of the scenario in Part 1, would the output be different? Why/why not?
e) Simulate the previous scenario and send a screenshot of the result.
f) Construct the circuit again in Logisim with 2 consecutive NOT gates instead of 3, and simulate the scenario in part d. Did the circuit operation change in this configuration? What would happen if 4 NOT gates were used? How about 5? Is there a pattern here that can lead to a general analogy regarding the number of the consecutive NOT gates? You should also submit the screenshot of the simulation result in this part.
g) BONUS QUESTION: What is the difference between the circuit in Part 1 and the circuit in Part 2? Which one is generally more preferred? Why? What can be the examples of the use cases of each circuit?
Part 3 -
Create the following digital circuit using Logisim and answer the following questions. Again, you are required to use the circuit you have created in Part 1 for this part.
The digital circuit has 2 inputs, C and D, and 2 outputs, Q and Q'. The circuit in Part 1 should be used twice in this configuration. They are referred to as L1 and L2.
The D input should be directly connected to the D input of L1 (D1).
The E input of L1 (E1) should be connected to the C input of this circuit satisfying the following expression:
E1 = NOT C
The Q output of L1 (Q1) should be directly connected to the D input of L2 (D2).
The E input of L2 should be directly connected to the input C.
The Q output of L2 (Q2) should be directly connected to the output Q.
The Q’ output of L2 (Q2’) should be directly connected to the output Q’.
a) What does this circuit do?
b) What does this circuit resemble?
c) What can be done with this circuit?
d) Explain, step by step, what happens in the following scenario:
- When Q' = 1, set Q' = 0.
- Then, set C = 0.
- Later, set D = 0.
- What happens when C is later on set to 1?
- While C is still 1, set D = 1. What is observed at the output in this case? What is the reason for the corresponding output? If this step were conducted at the end of the scenario in Part 1, would the output be different? Why/why not?
e) Simulate the previous scenario and send a screenshot of the result.
f) How does this circuit differ from the one in Part 1?
g) How does this circuit differ from the one in Part 2?
h) BONUS QUESTION: Name 2 advantages and 2 disadvantages for the circuit in Part 2 and for the circuit in Part 3.
Guidelines
- To create the digital circuit for Part 1, 2, and 3 use the LogiSim tool. Links for the download and guide of the tool can be found on the course main page.
- Tutorial on how to use NAND gate can be found here: http://www.cburch.com/logisim/docs/2.7/en/html/guide/attrlib/explore.html
- Once done with creating the circuit, take a snapshot of the circuit, and upload the snapshot. The uploaded file must be named as FIRSTNAME_LASTNAME_GROUP_TASK1_PART1.jpg, FIRSTNAME_LASTNAME_GROUP_TASK1_PART2.jpg, and FIRSTNAME_LASTNAME_GROUP_TASK1_PART3.jpg
- The "GROUP" part of the name of the submission refers to your study group (IASM or MAHM). If you are a system engineering student, put IASM instead of GROUP and same goes for MAHM.
- Answer the questions in each part in the reply box ("Online text" field when submitting. It is allowed to upload answers as a pdf-file too.
If you have any questions, please post them on the Course participant's forum (ask questions from a teacher/other participants). Other students are encouraged to participate in asking and answering questions.