Published on January 26th 2025 | 11 mins , 2188 words
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INTRODUCTION TO COMPUTERS
AND PRINCIPLES OF OPERATING SYSTEMS
November 2010
Time: 3 hours
THE KENYA NATIONAL EXAMINATIONS COUNCIL
DIPLOMA IN INFORMATION TECHNOLOGY
MODULE I
INTRODUCTION TO COMPUTERS AND
PRINCIPLES OF OPERATING SYSTEMS
3 hours
INSTRUCTIONS TO CANDIDATES
You should have the following for this examination:
Answer booklet.
Answer any FIVE of the following EIGHT questions.
All question carry equal marks.
This paper consists of 4 printed pages.
Candidates should check the question paper to ascertain that all the pages are printed as indicated and that no questions are missing.
2010 The Kenya National Examinations Council.
Turn over
1. (a) Outline two functions of the control unit in a computer system.(2 marks)
(b) State three disadvantages of a daisy wheel printer. (3 marks)
Can only print once font type/face
cannot do colour printing - it is monochrome
produces a lot of noise while printing
(c) (i) Distinguish between discretionary access and privileged access as used in file management. (1 mark)
Discretionary Access (DAC) - A security model where the owner of a file or resource decides who can access it and what permissions they have.
Privileged Access - Special access given to administrators or system users with elevated rights to manage system resources.
Discretionary Access (DAC) - Controlled by individual users (file owners).
Privileged Access - Controlled by system administrators or root users.
(ii) Classify the following DOS commands as either internal or external command: (4 marks)
Tree, chdir, fdisk, diskcopy, rmdir, format, xcopy, dir/p
(d) Describe the process of data transfer from the I/O devices to the main memory through direct memory access controllers. (8 marks)
2. (a) Explain the term disk quota as used in disk management. (2 marks)
A disk quota is a system feature that limits the amount of disk space a user or group can use on a storage device. It helps prevent individuals from consuming too much space, ensuring fair resource allocation and system stability.
(b) With the aid of a diagram, describe a typical logical layout of a primary disk partition. (6 marks)
A primary disk partition is a section of a hard drive that can store an operating system, files, and other data.
A primary partition is required for booting an OS.
Boot Sector (MBR)
File System (NTFS)
Data Area
Free Space
(c) With the aid of an example, explain the term device driver (2 marks)
A device driver is a specialized software program that allows an operating system (OS) to communicate with a specific hardware device. It acts as a translator between the hardware and the OS, ensuring that commands from the OS are executed correctly by the hardware.
When you print a document, the OS sends a request to the printer driver.
The printer driver translates this request into a format the printer understands.
The printer then executes the printing job based on the instructions from the driver.
(d) (i) A network system was discovered to be constantly experiencing deadlocks during inter process communication. Explain three ways in which the operating system could be designed in order to recover from the deadlocks. (6 marks)
(ii) For each of the following conditions of deadlock occurrence, state an appropriate prevention approach: (4 marks)
I. hold and wait;
II. mutual exclusion;
III. circular wait;
IV. no preemption.
3. (a) List four disadvantages of CRT monitors. (4 marks)
(b) With the aid of a diagram, describe a two-level directory structure. (5 marks)
(c) (i) Differentiate between incremental and differential backups as used in file management. (3 marks)
(ii) Explain the term utility software as used in operating systems. (2 marks)
(d) A hard disk with 25 tracks received requests from the disk drive controller for data in tracks 9, 2, 4, 17, 6 and 23 respectively. The disk has a seek time of 4 msec per track moved. Assuming that the head is initially at track 10, calculate the seek time needed for each of the following disk arm scheduling algorithms.
(i) shortest seek first; (6 marks)
(ii) first come first served.
4. (a) Explain two duties of an information systems manager in an organization. (4 marks)
5. (a) (i) Classify the following operating systems as either command based or graphical user interface:
Windows3.1, Unix, Linux, disk operating system, MAC/OS, OS/2, Novel, Windows XP. (4 marks)
(ii) Outline two sources of external interrupts during process execution. (2 marks)
(b) Differentiate between asymmetric and symmetric encryption methods of data security. (4 marks)
(c) With the aid of a diagram, explain a three-level scheduling system. (6 marks)
(d) A government department would like to convert their manual records to electronic form. Explain two circumstances that would influence the use of business process outsourcing services for the task. (4 marks)
6. (a) Outline four factors that could be considered when selecting an office printer other than cost. (4 marks)
(b) Explain the following terms as used in directory management giving an example in each case:
(i) absolute path name;
(ii) relative path name. (4 marks)
(c) (i) Figure 1 shows a network topology. Use it to answer the question that follows.
(ii) Outline four advantages of the network topology.
Figure 1
7. (a) (i) Explain the term stable write as used in disk management. (2 marks)
(ii) Differentiate between an assembler and an interpreter as used in computers.(4 marks)
(b) Explain the following terms as used in programmable clock systems:
(i) one-shot mode;
(ii) square-wave mode. (4 marks)
(c) With the aid of a diagram, describe the transitions within a three-process-state model during an inter-process communication. (6 marks)
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8. (a) Distinguish between a frame and a page as used in memory management. (4 marks)
(b) Explain the function for each of the following computer keyboard keys:
(i) print screen;
(ii) num lock.
(c) A processing system has four processes and six resources such that:
• Process A holds nothing but is requesting for resources 1 and 2;
• Process B holds resource 2 but is requesting for resources 4 and 6;
• Process C holds resource 3 but is requesting for resource 5;
• Process D holds resource 6 and is requesting for resources 2 and 5.
(i) Draw a resource allocation graph to represent this information. (6 marks)
(ii) State the processes that are deadlocked, if any, justifying your answer. (3 marks)
(d) Outline four principles of concurrency control during inter-process communication. (4 marks)
7. (a) (i) Explain the term ergonomics as applied in computers. (2 marks)
(ii) Outline four possible ways of minimizing glare in a computer working environment. (4 marks)
(b) Explain each of the following computer terms:
(i) data bus;
(ii) command language. (4 marks)
(c) Under what circumstance would each of the following types of schedulers be most appropriate:
(i) short term;
(ii) medium term. (4 marks)
(d) With the aid of a diagram, describe the monolithic structure model of an operating system. (6 marks)
6. (a) Outline four factors that could be considered when selecting an office printer other than cost. (4 marks)
(b) Explain the following terms as used in directory management giving an example in each case: (4 marks)
(i) absolute path name;
An absolute path is the full, complete path to a file or directory from the root directory.
It does not depend on the current location of the user or program. For example:
Linux/macOS:
/home/user/documents/report.pdf
Windows:
C:\Users\John\Documents\report.pdf
(ii) relative path name.
A relative path is the location of a file or directory relative to the current directory.
It depends on the current working directory (CWD).
Does not start with / (Linux/macOS) or C:\ (Windows).
Uses:
- . → Current directory
- .. → Parent directory
If the current directory is /home/user, then:
- documents/report.pdf → Refers to /home/user/documents/report.pdf
- .. /downloads/file.zip → Refers to /home/downloads/file.zip
(c) (i) Figure 1 shows a network topology. Use it to answer the question that follows.
(ii) Outline four advantages of the network topology. (4 marks)
5. (a) (i) Classify the following operating systems as either command based or graphical user interface:
Windows3.1, Unix, Linux, disk operating system, MAC/OS, OS/2, Novel, Windows XP. (4 marks)
(ii) Outline two sources of external interrupts during process execution. (2 marks)
(b) Differentiate between asymmetric and symmetric encryption methods of data security. (4 marks)
Symmetric Encryption uses One key (same for encryption & decryption) while Asymmetric Encryption uses Two keys (public & private)
Symmetric Encryption is faster while Asymmetric Encryption is slower
Symmetric Encryption is Less secure (key must be shared) while Asymmetric Encryption More secure (private key is secret)
symmetric encryption is used in File encryption, VPN, disk encryption while asymmetric is used in Digital signatures, SSL/TLS, email encryption
symmetric encryption uses AES, DES algorithms while Asymmetric uses RSA, ECC algorithms
(c) With the aid of a diagram, explain a three-level scheduling system. (6 marks)
(d) A government department would like to convert their manual records to electronic form. Explain two circumstances that would influence the use of business process outsourcing services for the task. (4 marks)
4. (a) Explain two duties of an information systems manager in an organization. (4 marks)
Ensuring the proper functioning of hardware and software systems.
Implementing cybersecurity measures to protect against data breaches, malware, and cyber threats.
Monitoring system performance and troubleshooting technical issues.
3. (a) List four disadvantages of CRT monitors. (4 marks)
consumes more power compared to flat panel displays
Covers more spaces compared to flat panel displays
produces/emits a lot of heat to the environment
It is very heavy hence not portable
(b) With the aid of a diagram, describe a two-level directory structure. (5 marks)
A two-level directory structure is a type of file system organization where each user has their own separate directory under a common root directory. This helps in organizing files efficiently and prevents name conflicts between users.
e.g C:/users1/juma/
C:/users2/omariba/
(c) (i) Differentiate between incremental and differential backups as used in file management. (3 marks)
(ii) Explain the term utility software as used in operating systems. (2 marks)
(d) A hard disk with 25 tracks received requests from the disk drive controller for data in tracks 9, 2, 4, 17, 6 and 23 respectively. The disk has a seek time of 4 msec per track moved. Assuming that the head is initially at track 10, calculate the seek time needed for each of the following disk arm scheduling algorithms.
(i) shortest seek first;
(ii) first come first served.
2. (a) Explain the term disk quota as used in disk management. (2 marks)
(b) With the aid of a diagram, describe a typical logical layout of a primary disk partition. (6 marks)
(c) With the aid of an example, explain the term device driver. (2 marks)
(d) (i) A network system was discovered to be constantly experiencing deadlocks during inter process communication. Explain three ways in which the operating system could be designed in order to recover from the deadlocks.
