MCD4700
Introduction to computer systems, networks and security
Assignment 1
Trimester 3, 2021
Submission guidelines
This is an individual assignment, group work is not permitted
Deadline: 2 December, 2021, 11:55pm
Submission format: docx for the written tasks, LogiSim circuit files for task 1, MARIE
assembly files for task 2. All files must be uploaded electronically via Moodle.
Late submission:
● By submitting a Special Consideration Form or visit this link:
https://lms.monashcollege.edu.au/course/view.php?id=1331
● Or, without special consideration, you lose 5 marks 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 Y marks, only Y-n*5 will be counted where n is the
number of days you submit late.
● Assessment items will not be accepted after more than 14 calendar days unless a
Special Consideration application has been approved. This 14-day time frame does
not apply to assessments due in Week 12.
In-class interviews: See instructions for Task 2 for details.
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. If there is any
evidence of copying (including from online sources without proper attribution), collaboration,
pasting from websites or textbooks, Zero marks may be awarded for the whole assignment,
the unit or you may be suspended or excluded from your course. Monash Colleges policies
on plagiarism, collusion, and cheating are available here or see this link:
https://www.monashcollege.edu.au/__data/assets/pdf_file/0010/17101/dip-assessment-policy.pdf
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.
https://lms.monashcollege.edu.au/course/view.php?id=1331
https://lms.monashcollege.edu.au/course/view.php?id=1331
https://www.monashcollege.edu.au/__data/assets/pdf_file/0010/17101/dip-assessment-policy.pdf
https://www.monashcollege.edu.au/__data/assets/pdf_file/0010/17101/dip-assessment-policy.pdf
1
1. Boolean Algebra and Logisim Task (35 marks)
Input Output
A B C D Z1 Z2
0 0 0 0 1 0
0 0 0 1 0 1
0 0 1 0 1 0
0 0 1 1 0 1
0 1 0 0 0 1
0 1 0 1 1 0
0 1 1 0 0 1
0 1 1 1 1 0
1 0 0 0 1 0
1 0 0 1 0 1
1 0 1 0 1 0
1 0 1 1 0 1
1 1 0 0 0 1
1 1 0 1 1 0
1 1 1 0 0 1
1 1 1 1 1 0
Truth table for Z1 and Z2
Step 1: Boolean Algebra Expressions (10 marks)
Write the Boolean equation for your truth table in sum of products form (your choice). First,
think about how to deal with the two outputs. Then, describe each single row in terms of
Boolean algebra. Finally, combine the Boolean terms for each row into a larger term. Briefly
explain these steps for the truth table given.
2
Step 2: Logical Circuit in Logisim (10 marks)
Model the resulting Boolean terms from Step 1 in a single Logisim circuit, using the basic gates
AND, OR, NOT. Use the original boolean expression for drawing the circuit (do not simplify
the expression). You can use logic gates with more than two inputs.
To do this task you have to use a template Logisim file “task_1.2_and_1.3_template” that has
been provided with this assignment. Do not forget to rename it and do not change the labels
or add any extra label, otherwise 2 marks will be detected.
Step 3: Optimised Circuit (15 marks)
The goal of this task is to find a minimal circuit (using only universal NAND gates). Based on
the truth table and Boolean algebra terms from Step 1, optimize the function using Karnaugh
maps.
You need to create two Karnaugh maps, one for each output. Your documentation should
show the maps as well as the groups found in the maps and how they relate to terms in the
optimized Boolean function. Then use Logisim to create a logic circuit. Don’t use any other
gates, other than NAND. Your documentation should also show how the equations have been
changed to “NAND only”. Use the template Logisim file “task_1.2_and_1.3_template” that has
been provided with this assignment. Do not forget to rename it.
Then use Logisim to create a logic circuit. Don’t use any other gates, other than NAND. Use
the template Logisim file “task_1.3_template” that have been provided with this
assignment. Do not forget to rename it.
3
2. MARIE (65 marks)
In this task you will develop a MARIE application that performs some manipulation of
characters, strings and numbers. We will break it down into small steps for you. Most of the
tasks require you to write code, test cases and some small analysis. The code must contain
comments, and you 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.
In-Class interviews: You will be required to demonstrate your code to your tutor after the
submission deadline. Failure to demonstrate will lead to “zero marks” being awarded to the
entire programming part of this assignment.
Name as a String
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 contiguous memory locations, with each address containing
one character.
● The characters are encoded using the ASCII encoding.
● End of a string is marked by the ASCII character ‘.’ (i.e. dot or full-stop).
● A string can be of any arbitrary length, and will be terminated by a ’.’, and it may
contain any of the following: alphabets (A-Z, a-z), numbers (0-9) and ASCII Space
Character (Hex 020).
Here is an example. A string “John Nguyen.” will be represented in memory (written as
hexadecimal numbers):
04A 06F 068 06E 020 04E 067 075 079 065 06E 02E
J o h n N g u y e n .
Note that, for a string with n characters, we need (n+2) words of MARIE memory in order to
store all the characters belonging to that string (including a space and a ‘.’ characters).
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When a program inputs a series of characters (i.e. a string is a sequence of characters) using
Unicode input mode, and stores them in the MARIE memory starting from location #0FFH, it
may look like the Figure 1 below. Note that all the entered characters (alphabets, numbers
and punctuation marks) are represented in ASCII (using Hexadecimal format).
Memory
Location
(Hex)
Memory
Content
Character
0FFH 048H ‘H’
100H 069H ‘i’
101H 020H ‘ ’
102H 04AH ‘J’
Figure 1 (a)
Memory
Location
(Hex)
Memory Content Character
103H 06FH ‘o’
104H 068H ‘h’
105H 06EH ‘n’
106H 02EH ‘.’
Figure 1 (b)
In MARIE assembly language programming, we can make use of the ADR command, the HEX
keyword and a label “myName” to store this string in memory:
myAdd, ADR myName
myName, HEX 04A /’J’
HEX 06F /’o’
HEX 068 /’h’
HEX 06E /’n’
HEX 020 /Space
HEX 04E /’N’
HEX 067 /’g’
HEX 075 /’u’
HEX 079 /’y’
HEX 065 /’e
HEX 06E /’n’
HEX 02E /’.’
5
Here, the label “myAdd” refers to the memory location of the label “myName”. So,
“myAdd=0001” referring to the first character ‘J.’
Instr.
No.
Memory
Location
Label Code Memory
Contents
1 000 myAdd, ADR myName 0001
2 001 myName, HEX 04A /J 004A
002 HEX 06F /o 006F
003 HEX 068 /h 0068
004 HEX 06E /n 006E
005 HEX 02E /Space 002E
006 HEX 04E /N 004E
007 HEX 06F //o 006F
008 HEX 061 //a 0061
009 HEX 068 //h 0068
00A HEX 02E //. 002E
Figure 2
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2.1 Write a MARIE program to encode your name and ID as a string (10
marks)
The following example of a MARIE string “nameID” encodes a name and an ID using ASCII
characters. The “name” is separated from the ID by an ASCII character “Hex 00A” (New Line).
Different parts of a name are separated by another ASCII character “Hex 020” (Space). And,
the string is terminated by a dot ‘.’ character. The label “addrNameID” holds the address of
the first character of the string. You need to follow this MARIE string while solving the task
given below.
addrNameID, ADR nameID
nameID, HEX 04A /’J’
HEX 06F /’o’
HEX 068 /’h’
HEX 06E /’n’
HEX 020 /Space
HEX 04E /’N’
HEX 067 /’g’
HEX 075 /’u’
HEX 079 /’y’
HEX 065 /’e’
HEX 06E /’n’
HEX 00A /NL(New Line)
HEX 032 /’2’
HEX 031 /’1’
HEX 032 /’2’
HEX 033 /’3’
HEX 039 /’9’
HEX 037 /’7’
HEX 039 /’9’
HEX 038 /’8’
HEX 02E /’.’
Encode a string that includes your full name (first name and last name) and your student ID
using ASCII characters. Following the above example, you need to use two labels, one label
(e.g. “nameID”) to store the first character of the string, and another label (e.g. “addrNameID”)
to store the address of the first character of the same string.
You need to use the ADR command and HEX keywords (like the above example), so that after
assembling, your name, ID and the address (of the first character of the string) is stored in
MARIE memory.
Document at least two test cases using screenshots of what the Memory (in MARIE) looks like
after saving the string into the memory (one test for your name and your ID and the other test
for anything). The document should be written into the report. Such as the screenshot in Figure
3.
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Figure 3
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2.2 Write a MARIE program to print the name and ID using subroutines
(10 marks)
Prepare a MARIE subroutine called subPrintString that can print the ASCII ‘.’ terminated
string of your name and your student ID that you have implemented above. You may use the
“Output” instruction to print characters in the MARIE output space.
To receive full marks, your program must have a subroutine to print the name and ID string.
The subroutine needs to be called from a MARIE main program using a JnS instruction.
Hint: In your main program, you need to use a label “StringAdd” that holds the start address
of the string (like, addrNameID) that you want to print. Then, you should call the subroutine
subPrintString. In the subroutine, the codes should then load a character from the
address “StringAdd”, print the character, then increment the address by one, and keep doing
that upto the character loaded from the address is a ‘.’ (which signals the end of the string).
The output may look similar to the output below.
John Nguyen
21239798
Document at least two test cases using screenshots of what the output screen and the Memory
(in MARIE) looks like after printing a string (one test for your name and your ID and the other
test for anything). The document should be written into the report. Such as the screenshot in
Figure 4.
Figure 4
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2.3 A subroutine to count the number of Alphabets in a string (15 marks)
Prepare a MARIE subroutine called subCountAlpha to count the number of alphabets ([‘A’
– ‘Z’] or [‘a’ – ‘z’]) that are present in the ASCII ‘.’ terminated string of your name and your
student ID that you have implemented in task 2.1. The subroutine also needs to print this
count (i.e. the total number of alphabets that are present in the string).
To receive full marks, your code needs to be in the form of a subroutine that can be called
using the JnS instruction. You need to write a MARIE main program to call this subroutine.
Hint: In your main program, you need to use a label “StringAdd” that holds the start address
of the string (like, addrNameID) that you want to use. Then, you should call the subroutine
subCountAlpha. In the subroutine, the codes should then load a character from that
address, include it in your count if it is an alphabet, then increment the address by one, and
keep doing that until the character loaded from the address is a ‘.’ (which signals the end of
the string). After completing the counting process, your program will print the count, for which
the output may look similar to the output below.
10
Document at least two test cases using screenshots of what the output screen and the
hardcoded name (in MARIE) looks like after printing a string (one test for your name and the
other test for anything). The document should be written into the report. Such as these
screenshots:
Figure 5
10
2.4 A subroutine to count the number of numeric characters in a string
(15 marks)
Prepare a MARIE subroutine called subCountNumerics that can count the number of
numeric characters [‘0’ – ‘9’] that are present in the ASCII ‘.’ terminated string of your name
and your student ID that you have implemented in task 2.1. The subroutine also needs to print
this count (i.e. the number of numeric characters that are present in the string).
To receive full marks, your code needs to be in the form of a subroutine that can be called
using the JnS instruction. You need to write a MARIE main program to call this subroutine.
Hint: In your main program, you need to use a label “StringAdd” that holds the start address
of the string (like, addrNameID) that you want to use. Then, you should call the subroutine
subCountNumerics. In the subroutine, the codes should then load a character from that
address, include it in your count if it is a numeric character, then increment the address by
one, and keep doing that until the character loaded from the address is a ‘.’ (which signals the
end of the string). After completing the counting process, your program will print the count, for
which the output may look similar to the output below.
8
Document at least two test cases using screenshots of what the output screen and the
hardcoded name (in MARIE) looks like after printing a string (one test for your name and the
other test for anything). The document should be written into the report. Such as this
screenshot:
Figure 6
11
2.5 A subroutine to read alphabets from keyboard, store them in a
string, and later, print the string (15 marks)
Prepare a MARIE subroutine called subSeperateAlpha that should read any character
from keyboard, and accepts only the alphabets ([‘A’ – ‘Z’] or [‘a’ – ‘z’]), to store in an ASCII ‘.’
terminated string. You need to store the ‘.’ character in the memory to mark the end of the
string. The subroutine also needs to print this string.
You may use the memory address “Hex100” or “Hex 200” to store your string depending on
the length of your program code. Ideally, the string location should be well higher in memory
than the last memory location used by your program.
To receive full marks, your code needs to be in the form of a subroutine that can be called
using the JnS instruction. You need to write a MARIE main program to call this subroutine.
Hint: In your main program, you need to use a label “StringAdd” that will hold a memory
location in MARIE as the start address of the string that you are going to enter from the
keyboard. Then, you should call the subroutine subSeperateAlpha. In the subroutine,
the codes should then read a character from the keyboard, accept it if it is an alphabet, then
increment the address by one, and keep doing that until the character entered is a ‘.’, which
signals the end of the data entry process. You need to store the ‘.’ character as well. After
completing the name entry process, your program will print the string, for which the output may
look similar to the output below.
Input: Australi3700a,.
Output: Australia
Figure 7
12
Document at least two test cases using screenshots of what the output screen and the
hardcoded name (in MARIE) looks like after printing a string (one test for your name and the
other test for anything). The document should be written into the report. Such as this
screenshot:
Figure 8
13
Files to be submitted:
One folder named “YourFirstNameLastNameStudentID” containing the following files:
1. Report for the written tasks (One Word file called YourFirstNameLastName
StudentID.doc / docx). The report should include your Full name, your student ID,
your class number and your tutor’s name.
2. Two Logisim files, one for task 1.2 and one for 1.3, name them LogicalCircuit.circ and
OptimizedCircuit.circ respectively.
3. MARIE files for tasks 2.1 to 2.5 name them as below:
● 2_1_NameIDString.mas
● 2_2_PrintNameID.mas
● 2_3_CountAlpha.mas
● 2_4_CountNumeric.mas
● 2_5_SeperateAlpha.mas
Zip the folder under the same name and submit it to moodle. You need to make sure there
are no spaces in any of the filenames.
NOTE! Your submitted files must be correctly identified (as described above).
Any submission that does not comply will receive an automatic 10 marks penalty
(applied after marking).