COS2621
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DISCLAIMER & TERMS OF USE
Educational Aid: These study notes are intended to be used as educational resources and should not be seen as a
replacement for individual research, critical analysis, or professional consultation. Students are encouraged to perform
their own research and seek advice from their instructors or academic advisors for specific assignment guidelines.
Personal Responsibility: While every effort has been made to ensure the accuracy and reliability of the information in
these study notes, the seller does not guarantee the completeness or correctness of all content. The buyer is
responsible for verifying the accuracy of the information and exercising their own judgment when applying it to their
assignments.
Academic Integrity: It is essential for students to maintain academic integrity and follow their institution's policies
regarding plagiarism, citation, and referencing. These study notes should be used as learning tools and sources of
inspiration. Any direct reproduction of the content without proper citation and acknowledgment may be considered
academic misconduct.
Limited Liability: The seller shall not be liable for any direct or indirect damages, losses, or consequences arising from
the use of these notes. This includes, but is not limited to, poor academic performance, penalties, or any other negative
consequences resulting from the application or misuse of the information provided.
, COS2621
1 Oct/Nov 2025
UNIVERSITY EXAMINATIONS
OCTOBER/NOVEMBER 2025
COS2621
Computer Organization and
Architecture
Exam date: 07 November 2025
11:45 am
Duration: 2 hours
Total marks: 80
Welcome to COS2621 exam.
This paper consists of 9 pages. Plus an appendix contains a list of x86 Assembly Language instructions.
Instructions:.
1. Students must upload their answer scripts in a single PDF file (answer scripts must
not be password protected or uploaded as “read only” files)
2. Incorrect file format and uncollated answer scripts will not be considered.
3. NO emailed scripts will be accepted.
4. You may use a “scrap” paper to work on. I would suggest that you write your student
number, name, and module code on the scrap paper. Show it to the IRIS recording
before the start of the exam, during and after the exam. This will allow the actual person
that will review your recording to take note of your scrap paper and what is written on it.
5. Students are advised to preview submissions (answer scripts) to ensure legibility and
that the correct answer script file has been uploaded.
6. Incorrect answer scripts and/or submissions made on unofficial examinations
platforms (including the invigilator cell phone application) will not be marked and no
opportunity will be granted for resubmission.
7. Mark awarded for incomplete submission will be the student’s final mark. No
opportunity for resubmission will be granted.
8. Mark awarded for illegible scanned submission will be the student’s final mark. No
opportunity for resubmission will be granted.
9. Submissions will only be accepted from registered student accounts.
10. Students who have not utilised invigilation or proctoring tools will be subjected to
disciplinary processes (only include if applicable).
11. Students suspected of dishonest conduct during the examinations will be subjected
to disciplinary processes. UNISA has a zero tolerance for plagiarism and/or any
other forms of academic dishonesty.
12. Students are provided one hour to submit their answer scripts after the official
examination time. Submissions made after the official examination time will be rejected
by the examination regulations and will not be marked.
13. Students experiencing network or load shedding challenges are advised to apply together
with supporting evidence for an Aegrotat within 3 days of the examination session.
14. Students experiencing technical challenges, contact the SCSC 080 000 1870 or email
or refer to URL link for the list of additional contact
numbers or
15. alternatively email your module lecturer. ONLY communication from your myLIfe account will
be considered.
ALL THE BEST!
Open Rubric
, COS2621
2 Oct/Nov 2025
SECTION A: General knowledge [60]
Choose from alternatives (1) to (5) the correct one. Each question counts 2 marks.
Question 1
The exists in one of two states and, in the absence of input, remains in that state.
(1) assert
(2) complex PLD
(3) decoder
(4) flip-flop
(5) oscillator
Question 2
instructions provide computational capabilities for processing numeric data.
(1) Boolean
(2) Logic
(3) Memory
(4) Arithmetic
(5) Comparison
Question 3
NASM is a(n) while DEBUG is a(n) .
(1) compiler, linker and loader
(2) assembler, assembler
(3) assembler, utility to assemble and debug programs
(4) translator, interpreter
(5) compiler, assembler
Question 4
Consider the following assembly language program fragment:
org 0x100
label1: dw 0x76EF
nop
mov ax,ax
nop
Which one of the following statements is true?
(1) 76h is stored in position 101h and EFh is stored in position 100h.
(2) 76h is stored in position 100h and EFh is stored in position 101h.
(3) 67h is stored in position 101h and EFh is stored in position 100h.
(4) 67h is stored in position 100h and EFh is stored in position 101h.
(5) None of the above.
Question 5
, COS2621
3 Oct/Nov 2025
Which number will be stored in the AX register if we key in the following instruction (exactly as it is) and
assemble it by using (i) NASM, and (ii) DEBUG?
mov ax,0024
(1) (i) AX = (0024)16 (ii) AX = (0024)16
(2) (i) AX = (0024)10 (ii) AX = (0024)10
(3) (i) AX = (0024)16 (ii) AX = (0024)10
(4) (i) AX = (0024)10 (ii) AX = (0024)16
(5) None of the above.
Question 6
A logical cache stores data using _.
(1) physical addresses
(2) virtual addresses
(3) random addresses
(4) both (1) and (3)
(5) direct addresses
Question 7
Consider the following pseudo-ops (use NASM):
org 0x100
db 'Q'
dw 213h
db 15
In which relative memory location will (i) 51h and (ii) (15)10 respectively be stored?
(1) (i) 0000h (ii) 0003h
(2) (i) 0002h (ii) 0002h
(3) (i) 0003h (ii) 0001h
(4) (i) 0001h (ii) 0002h
(5) None of the above.
Question 8
Suppose a machine has twelve (12) general-purpose 32-bit registers. How many bits must be reserved in the
machine code instruction in order to address any one of these twelve registers?
(1) 1
(2) 2
(3) 3
(4) 4
(5) 5
Question 9
Which one of the following instructions would you use if you want to branch to the label TEST if the sign flag is
set?
(1) JN TEST
(2) JZ TEST
(3) JS TEST
(4) JNS TEST
(5) JNP TEST
Question 10
Which of the following are characteristics of Blu-ray DVDs?
a. They can store more than 20 GB per side.
EXAM PACK
Recent exam questions and answers
Summarised study notes
Exam tips and guidelines
+27 81 278 3372
DISCLAIMER & TERMS OF USE
Educational Aid: These study notes are intended to be used as educational resources and should not be seen as a
replacement for individual research, critical analysis, or professional consultation. Students are encouraged to perform
their own research and seek advice from their instructors or academic advisors for specific assignment guidelines.
Personal Responsibility: While every effort has been made to ensure the accuracy and reliability of the information in
these study notes, the seller does not guarantee the completeness or correctness of all content. The buyer is
responsible for verifying the accuracy of the information and exercising their own judgment when applying it to their
assignments.
Academic Integrity: It is essential for students to maintain academic integrity and follow their institution's policies
regarding plagiarism, citation, and referencing. These study notes should be used as learning tools and sources of
inspiration. Any direct reproduction of the content without proper citation and acknowledgment may be considered
academic misconduct.
Limited Liability: The seller shall not be liable for any direct or indirect damages, losses, or consequences arising from
the use of these notes. This includes, but is not limited to, poor academic performance, penalties, or any other negative
consequences resulting from the application or misuse of the information provided.
, COS2621
1 Oct/Nov 2025
UNIVERSITY EXAMINATIONS
OCTOBER/NOVEMBER 2025
COS2621
Computer Organization and
Architecture
Exam date: 07 November 2025
11:45 am
Duration: 2 hours
Total marks: 80
Welcome to COS2621 exam.
This paper consists of 9 pages. Plus an appendix contains a list of x86 Assembly Language instructions.
Instructions:.
1. Students must upload their answer scripts in a single PDF file (answer scripts must
not be password protected or uploaded as “read only” files)
2. Incorrect file format and uncollated answer scripts will not be considered.
3. NO emailed scripts will be accepted.
4. You may use a “scrap” paper to work on. I would suggest that you write your student
number, name, and module code on the scrap paper. Show it to the IRIS recording
before the start of the exam, during and after the exam. This will allow the actual person
that will review your recording to take note of your scrap paper and what is written on it.
5. Students are advised to preview submissions (answer scripts) to ensure legibility and
that the correct answer script file has been uploaded.
6. Incorrect answer scripts and/or submissions made on unofficial examinations
platforms (including the invigilator cell phone application) will not be marked and no
opportunity will be granted for resubmission.
7. Mark awarded for incomplete submission will be the student’s final mark. No
opportunity for resubmission will be granted.
8. Mark awarded for illegible scanned submission will be the student’s final mark. No
opportunity for resubmission will be granted.
9. Submissions will only be accepted from registered student accounts.
10. Students who have not utilised invigilation or proctoring tools will be subjected to
disciplinary processes (only include if applicable).
11. Students suspected of dishonest conduct during the examinations will be subjected
to disciplinary processes. UNISA has a zero tolerance for plagiarism and/or any
other forms of academic dishonesty.
12. Students are provided one hour to submit their answer scripts after the official
examination time. Submissions made after the official examination time will be rejected
by the examination regulations and will not be marked.
13. Students experiencing network or load shedding challenges are advised to apply together
with supporting evidence for an Aegrotat within 3 days of the examination session.
14. Students experiencing technical challenges, contact the SCSC 080 000 1870 or email
or refer to URL link for the list of additional contact
numbers or
15. alternatively email your module lecturer. ONLY communication from your myLIfe account will
be considered.
ALL THE BEST!
Open Rubric
, COS2621
2 Oct/Nov 2025
SECTION A: General knowledge [60]
Choose from alternatives (1) to (5) the correct one. Each question counts 2 marks.
Question 1
The exists in one of two states and, in the absence of input, remains in that state.
(1) assert
(2) complex PLD
(3) decoder
(4) flip-flop
(5) oscillator
Question 2
instructions provide computational capabilities for processing numeric data.
(1) Boolean
(2) Logic
(3) Memory
(4) Arithmetic
(5) Comparison
Question 3
NASM is a(n) while DEBUG is a(n) .
(1) compiler, linker and loader
(2) assembler, assembler
(3) assembler, utility to assemble and debug programs
(4) translator, interpreter
(5) compiler, assembler
Question 4
Consider the following assembly language program fragment:
org 0x100
label1: dw 0x76EF
nop
mov ax,ax
nop
Which one of the following statements is true?
(1) 76h is stored in position 101h and EFh is stored in position 100h.
(2) 76h is stored in position 100h and EFh is stored in position 101h.
(3) 67h is stored in position 101h and EFh is stored in position 100h.
(4) 67h is stored in position 100h and EFh is stored in position 101h.
(5) None of the above.
Question 5
, COS2621
3 Oct/Nov 2025
Which number will be stored in the AX register if we key in the following instruction (exactly as it is) and
assemble it by using (i) NASM, and (ii) DEBUG?
mov ax,0024
(1) (i) AX = (0024)16 (ii) AX = (0024)16
(2) (i) AX = (0024)10 (ii) AX = (0024)10
(3) (i) AX = (0024)16 (ii) AX = (0024)10
(4) (i) AX = (0024)10 (ii) AX = (0024)16
(5) None of the above.
Question 6
A logical cache stores data using _.
(1) physical addresses
(2) virtual addresses
(3) random addresses
(4) both (1) and (3)
(5) direct addresses
Question 7
Consider the following pseudo-ops (use NASM):
org 0x100
db 'Q'
dw 213h
db 15
In which relative memory location will (i) 51h and (ii) (15)10 respectively be stored?
(1) (i) 0000h (ii) 0003h
(2) (i) 0002h (ii) 0002h
(3) (i) 0003h (ii) 0001h
(4) (i) 0001h (ii) 0002h
(5) None of the above.
Question 8
Suppose a machine has twelve (12) general-purpose 32-bit registers. How many bits must be reserved in the
machine code instruction in order to address any one of these twelve registers?
(1) 1
(2) 2
(3) 3
(4) 4
(5) 5
Question 9
Which one of the following instructions would you use if you want to branch to the label TEST if the sign flag is
set?
(1) JN TEST
(2) JZ TEST
(3) JS TEST
(4) JNS TEST
(5) JNP TEST
Question 10
Which of the following are characteristics of Blu-ray DVDs?
a. They can store more than 20 GB per side.
