• switches can send and receive data simultaneously - they are full duplex
• a hub is half duplex- only one host can communicate at a time.
• a hub broadcast signals to all computers connected in a network while a switch directs data to its intended destination

• It requires that a foreign key must have a matching primary key or it must be null

Advantages of  of Hard Disk Drive

• Hard disk drives are cheaper per gigabyte than solid state drives.
• Hard disks have a longer lifespan than solid state drives

Disadvantages of Hard Disk Drives

• Consumes more power than SDD
• They are noisy.
• They are slower than solid state drives.
• They are susceptible to wear and tear as they have movable parts.

Advantages of Solid State Drives

• Are faster than HDDs
• It is more durable as it does not have moving parts
• Consumes less power
• Are not noisy

Disadvantages of SDD

• It costs more than a conventional hard disk
• Have fewer write/erase cycles compared to a hard disk drive
• Lost data cannot not be recovered

1. Overheating: Smoke and dust particles can accumulate inside the computer's casing, blocking airflow and hindering the cooling mechanisms of the computer. This can lead to overheating of the internal components, such as the CPU and graphics card. Overheating can cause system instability, performance degradation, and even permanent damage to the hardware.

2. Component Malfunction: Smoke and dust particles can settle on electronic components, such as the motherboard, memory modules, and connectors. Over time, this accumulation can create a layer of debris, leading to poor electrical contact and interference with signal transmission. This can result in component malfunctions, intermittent failures, or even complete hardware failure.

3. Short Circuits: If smoke or dust particles contain conductive materials, such as metal flakes or moisture, they can create a risk of short circuits. When conductive particles come into contact with exposed circuits or connectors, they can cause a direct electrical connection between two points that are not intended to be connected. Short circuits can damage components, disrupt data transmission, and even pose a fire hazard.

4. Increased Maintenance Requirements: Smoke and dust particles can increase the frequency and complexity of computer maintenance. Accumulated dust can clog cooling fans, causing them to work less effectively or even fail. Additionally, smoke particles can leave behind sticky residues that further attract dust, making the cleaning process more challenging.

5. Reduced Performance and Reliability: As smoke and dust particles accumulate within the computer, they can restrict the movement of mechanical components, such as fans or disk drives, affecting their performance and reliability. Dust particles can also hinder the reading and writing capabilities of optical drives or cause errors in data transmission.

• two's complement has only one value for zero

Physical topology - the physical arrangement of nodes of a computer network

Examples

• bus topology
• ring topology
• mesh topology
• star topology

Logical topology- the way data flows in a network

Examples

• Ethernet
• Ring

(i) State the name of this protocol.   HTTPS 

(ii) Identify how this protocol changes the data to transmit the data securely.

• It encrypts it
• It applies encryption algorithm
• It applies an encryption key

• It sends control signals that manage the transfer of data and instructions within the CPU
• It decodes an instruction using an instruction set

• online storage
• incremental backup
• full backup
• RAID (level 0, 1, 10)
• uninterruptible power supply (UPS)

(i) Jobs collected together for processing at a later time
(ii) Output produced quickly enough to affect the next input
(iii) User has direct contact with the processor
(iv) User cannot communicate directly with the processor

• an use Internet connection and telephone at the same time
• much faster data transfer speed
• always “on”
• charged for number of bytes/flat rate per month rather than actual time on line
• more bandwidth

specify output requirements
design documents/screen displays
data for input/storage
form design
storage devices
file structures/access/design
data security/back up files
systems flowchart etc.
implementation i.e. pilot/intermediate/parallel running
testing strategy
training
hardware/software
programming/algorithms
validation
user manual
technical documentation
entering data into system

• understand the current system
• produce data flow diagrams/system flowchart
• identify user/client requirements/objectives
• interpret user/client requirements/objectives
• agree requirements/objectives with the user/client
• collect data from the current system
• fact finding (e.g. questionnaires, interviewing, etc.)
• problem identification

• confidentiality - The principle of protection from unauthorized access or disclosure
• Integrity - the principle of ensuring that unauthorized or undetected changes to data or system configurations do not occur.
• Availability - the principle of ensuring that data and services remain accessible to authorized users at all times

• Software may be designed to run on 1 core and not multiple cores
• depends on the task(s)  i.e some tasks cannot be split across cores
• Clock speed also affects speed i.e dual core may have a faster clock speed and quad-core may have slower clock speed so one task may be run faster/slower
• RAM size also affects speed i.e Quad-core may have less RAM  amount of VM being used
• Cache size also affects speed i.e Quad-core may have less cache

• It is a utility software that places file data in adjacent sectors to free up space for more data and reduce access time for files stored

17. a) i) Explain the term search as used in the Internet.                                            [2]

A web based application that locates items or information from the World Wide Web

ii) Peter intends to download a movie from the Internet. State the three factors that may determine the total time taken to complete the download.                                           [3]

• Size of the video/format
• The bandwidth of the media/speed of network/network traffic
• Type of browser software
• Background activities running in the computer
• Restrictions enforced in the computer/firewall/antivirus
• Speed of the computer/CPU speed
• Size of RAM

b) Wakulima online is an organization that runs a web based system for assisting farmers to obtain market for their produce. State four technological reasons that may cause a farmer not to access the organization’s system.                                                                                  [4]

• Poor network/lack of connection
• Software failure in the system

• Hardware failure
• Lack of access rights
• System overload/hanging
• Lack of skills/disability/illiteracy
• Lack of power supply

c) Explain a situation when each of the following Desktop Publishing program features may be used when creating a publication:

i. Cropping                                                                                                               [2]

Applies to graphics – used to trim/remove/hide some portions in the graphics

ii. Transparency                                                                                                         [2]

Used to make background of a graphic to be clear/visible

d. List two areas where infrared waves are used in data communication.                             [2]

18. a) List four activities of the planning stage of systems development.                             Ignore this question, marks redistributed elsewhere

b) Explain a circumstance when each of the following feasibility studies are carried out during systems development.

i. Technical                                                                                                               [3]

Done to determine whether technology exists to support the proposed solution

ii. Economic                                                                                                              [3]

Done to determine whether the proposed solution is economically viable

iii. Schedule                                                                                                               [3]

Done to determine whether the proposed system can be done within an acceptable time.

c) Table 1 and Table 2 are related tables in a database. Use them to answer the questions that follow.

Table 1

Table 2

i. Identify the appropriate primary key for each table.                    [2]

Table 1 – Dept code, Student Registration No

ii. Explain two benefits of enforcing referential integrity in the database. [4]

• No record can be added in Table 2 if its corresponding record in Table 1 does not exist
• No record in Table 1 can be deleted without first deleting the corresponding record in Table 2
• Reduces data redundancies/ensures integrity
• Prevents deletion of related table

19. a) Describe each of the following validation checks as used in data processing.

i. Preserve check                                                                                                      [2]

Ignore this question, marks redistributed elsewhere

ii. Data type check                                                                                                    [2]

Ensure correct type of data is entered for the field

iii. Check digit                                                                                                           [2]

This is a number added/calculated by the computer to a binary number. The check digit ensures correct transmission of the binary number.

b. Write each of the following abbreviations in full:

i) BCD                                                                                                                                    [1½]

Binary Coded Decimal

ii) EBCD                                                                                                                                 [

This question was thrown out and marks redistributed elsewhere

iii) ASCII                                                                                                                    [1½]

American Standard Code for Information Interchange

c) Using 10-bits binary number system, perform the following decimal operation using two’s complement.                                                                                                                                   [6]

12910 - 12810

+129 = 00 1000 0001

128 = 00 1000 0000

-128 = 11 0111 1111 (ones complement)

                            +1

          11 1000 0000 (Twos complement)

129- 128

     00 1000 0001

+ 11 1000 0000

 100 0000 0001

Hence = 00 0000 00012 or 12 (the overflow bit is ignored)

Phased:
Advantages:

• only a small part of the operation affected if new system fails
•  no need to pay for two sets of wages

Disadvantages:

•  time consuming (each part needs testing fully before expanding system)

Pilot:
Advantages:

• if new system fails, only that part will be affected
• possible to gradually train staff on pilot before whole system changes over

Disadvantages:

•  time consuming (waiting to see how pilot works before rolling out to rest of the organisation)

Direct:
Advantages:

•  less likely to malfunction since fully tested
• immediate benefits/less time wasted
•  reduced costs (only one system so no need to duplicate staff)

Disadvantages:

• disastrous if the new systems does fail

Parallel:
Advantages:

•  if new system goes down, there is a backup system in place
• possible to gradually train staff/staff have time to get used to the new system

• Realtime processing
• Batch processing
• Timesharing
• multiprogramming
• Online
• Batch
• Distributed

1. Slow Performance: If your computer suddenly becomes significantly slower than usual, taking longer to boot up, open applications, or respond to commands, it could be a sign of a virus. Viruses can consume system resources, resulting in decreased performance.

2. Frequent Crashes: If your computer frequently crashes, freezes, or experiences sudden system reboots without any apparent reason, it could be due to a virus. Some viruses can interfere with system stability, leading to unexpected crashes or instability.

3. Unusual Pop-ups or Ads: If you start noticing an excessive number of pop-ups, advertisements, or banners appearing on your computer screen, especially when you're not browsing the internet, it might be an indication of adware or malware infection.

4. Unwanted Modifications: Viruses can modify system settings or configurations without your consent. If you observe changes in your default browser homepage, new toolbars appearing, unfamiliar icons on the desktop, or altered settings, it could be a sign of a virus.

5. Unusual Network Activity: If you notice excessive network traffic, unusual data transfers, or a sudden increase in data usage without any known reason, it could be an indication of a virus or malware actively communicating with external servers.

6. Missing or Modified Files: Viruses can delete, encrypt, or modify files on your computer. If you find missing files or encounter unexpected changes in file sizes, names, or extensions, it could be a result of a virus infection.

7. Disabled Security Software: Some viruses attempt to disable or circumvent antivirus or security software to avoid detection. If you notice that your antivirus program or firewall is deactivated, modified, or unable to update, it could be due to a virus compromising your security software.

8. Unexpected Email or Message Activity: Viruses can use infected computers to send spam emails or messages to contacts in your address book without your knowledge. If your friends or colleagues report receiving suspicious or unexpected emails or messages from you, it could be a sign of a virus.