FIT1047 – Introduction to Computer Systems, Networks and Security
Assignment-1 Semester 1, 2020
Submission guidelines
This is an individual assignment, group work is not permitted.
Deadline: Assignment 1 due by week-7, Friday 4:00 PM.
Submission format: PDF for the written tasks, LogiSim circuit files for task 1, MARIE assembly files for task 2. All files must be uploaded electronically via Moodle. More details at the end of the assignment specifications.
Individualised exercises: Some exercises require you to pick one of several options based on your student ID.
Late submission:
• By submitting a Special Consideration Form with supporting documentation.
• Or, without special consideration, you lose 5% of your mark per day that you submit late
(including weekends). Submissions will not be accepted more than 5 days late.
This means that if you got x marks, only 0.95n × x will be counted where n is the number of days you submit late.
Marks: This assignment will be marked out of 100 points, and count for 20% of your total unit marks.
Plagiarism: It is an academic requirement that the work you submit be original. Zero marks will be awarded for the whole assignment if there is any evidence of copying (including from online sources without proper attribution), collaboration, pasting from websites or textbooks. Further Note: When you are asked to use internet resources to answer a question, this does not mean copy-pasting text from websites. Write answers in your own words such that your understanding of the answer is evident. Acknowledge any sources by citing them. Your work will be submitted and compared with previous students works and also on the internet for plagiarism using Turnitin software. So please make sure the submission is your work.
1. Boolean Algebra and Logisim Task
The following truth table describes a Boolean function with four input values X1, X2, X3, X4
and two output values Z1, Z2.
X1
X2
X3
X4
Z1
Z2
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
1
1
0
1
0
1
1
1
0
1
1
0
0
1
0
1
0
1
1
1
0
1
1
0
1
1
0
1
1
1
1
0
The main result of this task will be a logical circuit correctly implementing this Boolean function in the Logisim simulator. Each step as defined in the following sub-tasks needs to be documented and explained.
1.1 Task 1: Boolean Algebra Expressions (10 points)
Write the Boolean function as Boolean algebra terms, using, either Product of Sum (POS) or Sum of Product (SOP) method. First, think about how to deal with the two outputs. Then, describe each single row in terms of Boolean algebra. e.g. combine the inputs (A, B, C, & D) to form a POS or SOP terms for each row. Finally, combine the terms for single rows into larger terms. As, Z1 and Z2 are two separate outputs, you need to deal with them separately.
Briefly explain these steps for your particular truth table (e.g., explain for one particular row how you come up with the Boolean terms for that row, and then explain how you combine all rows). This explanation should be no more than a few sentences.
Notation: use the following symbols and notation for writing Boolean algebra expressions. Variables are upper-case (e.g., A, B, C, D, X1, Z2). Boolean AND is written without a symbol, e.g. X1X2. Boolean OR is written with the + symbol, e.g. X1+X2. Negation is written
using an overline, e.g. 𝑋𝑋1 . Important: when writing terms like NOT X1 AND NOT X2, there must be a clear gap in the overlines, e.g. 𝑋𝑋1 𝑋𝑋2
1.2 Task 2: Logical circuit in Logisim (20 points)
Model the resulting Boolean terms from Step 1 in a single Logisim circuit, using only the basic gates AND, OR, NOT. You can use gates with more than two inputs. The single logic circuit should show all the four inputs, and both the outputs Z1 & Z2. The outputs should not be split up into two circuits.
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1.3
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Briefly explain your construction (as for Step 1, a short explanation is enough). Test you circuit using values from the truth table and document the tests.
Task 3: Optimized circuit (20 points)
The goal of this task is to find a minimal circuit using only AND, OR, and NOT gates. Based on the truth table and Boolean algebra terms from Step 1.
1. Subtask-1: Optimize the function using Karnaugh maps to its minimal form
2. Subtask-2: Optimize the function using Boolean identities and verify its minimal form
from the subtask-1
You will need to create two Karnaugh maps and work on two separate Boolean Identities reduction forms, one for each output Z1 & Z2. Your documentation must show
a) the K-Maps.
b) the groups found in the K-Maps
c) The two Boolean identities reduction for Z1 & Z2 with steps.
d) And compare and contrast the two methods (K-Map & Boolean Identities methods)
show how they relate to terms in the optimized Boolean function.
Then use Logisim to create a minimal circuit, using only AND, OR, and NOT gates. Test your optimized circuit using values from the truth table and document your tests.
Note you can use Product-of-Sum or Sum-of-Product to optimise in subtask-2
2. MARIE (50 Marks)
In this task you will develop a MARIE application that performs some manipulation of strings. We will break it down into small steps for you.
Most of the tasks require you to write the code, test cases and some small analysis. The code must contain comments, and you must submit it as .mas files together with the rest of your assignment. The test cases should also be working, self-contained MARIE assembly files (without requiring much input from the user). The analysis needs to be submitted as part of the main PDF file you submit for this assignment.
Name as Strings
This section introduces the concepts you need for the rest of the assignment.
A string is a sequence of characters. It’s the basic data structure for storing text in a computer. There are several different ways of representing a string in memory and how to deal with strings of arbitrary length.
For this assignment, we will use the following string representation:
● A string is represented in a contiguous memory location, with each address containing a single character.
● The characters are encoded using the ASCII encoding.
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● End of a string is marked by the ASCII character ‘0’.
● A name will be composed of two strings, namely, First Name and Last Name.
● End of a name will be marked by another ASCII character ‘0’.
As an example, this is how, a name “John Noah” would be represented in memory (written as hexadecimal numbers):
Note that for a string with n characters, we need n + 3 words of memory in order to store all the characters belonging to a first name, last name and the additional ‘0’s that marks the end of each of the two strings, i.e. First Name and Last name, and end of the name.
In MARIE assembly language programming, we can make use of the ADR command, the HEX keyword and a label “myName” to put this string into memory:
myNameAdd, ADR myName myName, HEX 04A //J HEX 06F //o HEX 068 //h HEX 06E //n HEX 030 //0
HEX 04E //N HEX 06F //o HEX 061 //a HEX 068 //h HEX 030 //0 HEX 030 //0
2.1 Write a main program and a subroutine for entering minimum of three names from the keyboard and printing them at the end of data entry. (25 marks)
Prepare a MARIE program to enter your full name using Unicode / ASCII characters. You should be able enter at most 5 characters for each part of your name (First Name or Last Name)– if your name is longer, you can shorten it (limit the maximum number of characters per full name to 11, including the space character).
You need to submit a MARIE file that contains code, so that after assembling and running the program it should prompt for first name and last name. The program should store full names in MARIE memory and print them at the end.
The code should focus on getting the full names as input from keyboard and storing them in a particular location in MARIE memory. For this task, prepare a MARIE subroutine called
04A
06F
068
06E
030
04E
06F
061
068
030
030
J
o
h
n
0
N
o
a
h
0
0
3
subInputNames to input names from keyboard. Your subroutine should take (Unicode /ASCII) ‘0’ terminated First name and (Unicode /ASCII) ‘0’ ‘0’ terminated Last name as described in the previous section. The names are to be stored starting from the memory address 300H. A single
name (First Name and Last Name) in a row of MARIE memory. After entering a last name, a second Unicode/ASCII ‘0’ will be stored to mark the end of the full name in the memory, and the program should proceed to take the next name, which is to be stored at memory location 310H. This location is one row (16 words) ahead from the memory location of the previous name
entry. You can use memory locations 320H, 330H , … to store more names respectively. After entering a full name, a ‘$’ from input will terminate the entire name entry process and will return control to the calling program. You may need to store the ‘$’ entered instead of ‘0’ ‘0’ and consider that as the placeholder for the end of the sequence. Your program must take names infinitely until a user enters a ‘$’ to stop taking inputs. You can verify the correct working of your program by viewing the memory content starting from #300H.
Then, in the second part of the code is to prepare a MARIE subroutine called printStringName that can print all the full names stored, i.e. it should print out the full names entered earlier and saved by the program (using the “Output” instruction).
Start by using a label “PrintName” that holds the start address of a name string (like, myNameAdd in the example above). The code should then load a character from that address, output it if it is not ‘0’, then increment the address by one, and keep doing that until the character loaded from the address is a ‘0’ (which signals the end of the string / end of the first name). Then, print an ASCII “Space” character, and proceed to print the second part of the name string, i.e. Last Name until the character loaded from the address is a ‘0’ (which signals the end of the string / end of the last name). Then, when you load the second ASCII ‘0’ which marks the “end of a name”, print an ASCII “New Line” character and proceed to print the next name. If the loaded character is ‘$’, the subroutine needs to stop printing and gives control to the main program. For this task, you may use three names (your First Name and Last Name, your friend’s name and your tutor’s name) to enter from keyboard and also to print the names after entering the three names, the names should not be hard coded and assigned a label to identify each of the three names.
To receive full marks, your code needs to be in the form of a main program and use of subroutine that can be called using the JnS instruction. You need to write a MARIE main program to call the subroutine you created accordingly. Save your code as “2_1_Enter_and_PrintingNames.mas”.
2.2 A three function Calculator in MARIE (25 marks)
In this task you will develop a MARIE program that performs three mathematical functions of a calculator – multiplication, division and exponent.
The program should be performing the user selected tasks (one of the mentioned mathematical operations) after the user enters one of the selections, ‘m’, ‘d’, or ‘e’. Here, input ‘m’ selects
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multiplication process, ‘d’ selects division process and ‘e’ is for calculating exponent. User enters ‘q’ to quit the program. If the user input is ‘m’, ‘d’, or ‘e’, then the program should ask
for operands x and y and displays the result. Example:
• INPUT SELECTION = ‘m’ and the input numbers are ‘x’ & ‘y’ then the resultant output = ‘x * y’
• INPUT SELECTION = ‘d’ and the input numbers are ‘x’ & ‘y’ then the resultant output = ‘x/y’
• INPUT SELECTION = ‘e’ and the input numbers are ‘x’ & ‘y’ then the resultant output = ‘xy’
• INPUT SELECTION = ‘q’ simply quits the program and exit. The program should run infinitely, until a user enters ‘q’.
You are required to write subroutines (for each operation) to perform these tasks (multiplication, division and exponent) and write a main program to process user operation selection, accept the ‘x’ & ‘y’ inputs and call the appropriate subroutine thereof. The codes must contain comments, as a paragraph before any block of code (i.e. subroutine) or as inline comments wherever appropriate. You should submit the “2_2_Calculator.mas” file together with the rest of your assignment.
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Files to be submitted:
One zipped folder named “YourFirstName_LastName_StudentID.zip” containing the following files.
1. Report for the written tasks
(One PDF file called YourFirstName_LastName_ StudentID.pdf).
a. The report should include your Full name, your student ID, your class number and your tutor’s name.
b. Include the original truth table in the pdf.
c. The pdf report should show the workings for the following:
i. Subtask-1: Optimize the function using Karnaugh maps to its minimal form
ii. Subtask-2: Optimize the function using Boolean identities and verify its minimal form from the subtask-1.
iii. You will need to include two Karnaugh maps worked on two separate Boolean Identities reduction forms, one for each output Z1 & Z2. Your documentation must show
1. the K-maps.
2. the groups found in the maps
3. The Boolean identities reduction steps
4. and how they relate to terms in the optimized Boolean function.
d. Documentation related to Task 2, if there is any.
2. Task 1.2 – Logisim File. Name the file as “LogicCircuit.circ”.
3. Task 1.3 – Logisim File. Name the file as “OptimizedCircuit.circ”
4. Task 2.1 – MARIE File. Name the file as “2_1_Enter_and_PrintingNames.mas”
5. Task 2.2 – MARIE File. Name the file as “2_2_Calculator.mas”
Zip the folder with this name (YourFirstName_LastName_StudentID.zip) and submit it to Moodle. You need to make sure there are no spaces in any of the filenames.
End of Assignment 1
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