• user changes his mind
• new government legalisation/company policy company changes
• changes in hardware
• changes in software/upgrades/new versions
• improved operating efficiency/ease of use

• Hierarchical model  - Records in the database can be related to one parent only but can have more children records
• Network database model - a child record can be linked to  multiple parent records
• Relational database model - organizes data into tables that can be linked or related based on data common to each.

• Extra bit on each data-byte that
•  Does not transmit data
• Makes the number of ones in a byte always even or always odd
• Error in the transmission of a bit will make the even/odd wrong
• The problem of two errors in one byte not being found
• Parity block

Explain the purpose of each of the following features of a spreadsheet chart (KCSE 2021, Q19 (a))

Legend

• Legends are a small visual representation of the chart's data series to understand each without confusion.

A data series

• is a row or column of numbers that are entered in a worksheet and plotted in your chart, such as a list of quarterly business profits
• A group of related data points or markers that are plotted in charts and graphs

Data Marker

• A symbol on the chart that represents a single value in the worksheet.
• A column, dot, pie slice, or another symbol in the chart representing a data value

https://www.lifewire.com/data-series-data-points-data-labels-3123411

Advantages

• no wires
• fast/high-speed wireless Internet access
• WLAN is faster than a modem or mobile
• WLAN for working at home one day a week/teleworkers
• see internet content away on the move
• create and send multimedia messages to mobiles or e-mail
• picture messaging - send photos/pictures text/sound/recorded
• greetings from mobiles to mobiles/PCs
• instant transmission - no busy signals/no searching for phone jacks
• download e-mail and file attachments on mobile
• watch live webcast on mobile/hotspot
• listen to streaming video on mobile/hotspot
• news/weather/sport/games while on the move
• access information from mobile anytime
• send/receive/delete e-mail while on the move
• wireless Inbox on mobile - to contacts and calendar
• view business appointments while out of the office on mobile
• send corporate e-mail while out of the office - even behind a firewall on mobile
• wireless internet connection from chat rooms for discussions with colleagues while on the move
• give visual demonstrations from mobile and colleagues watch back at the office

 disadvantages e.g.

• WLAN speeds are slower than Net access at work/narrow band width
• any one within the WLAN nodes range with an appropriate device can use your WLAN and broad band link
• any one who walks past your house or WLAN linked into a corporate system can access sensitive information or credit card details
• 3G phones not compatible with 2G phones
• Blue tooth - has limited range
• blocked signal/distorted signal/weak signal/lag
• health problems from microwaves

• It covers many aspects that will be used to decide whether to go ahead with the project or not.
• The main components are technical, operational, economic, legal and scheduling.

- Passwords
- Hierarchy
- Only allow some staff to access student files
- Only some machines able to access
- Physical location of these machines
- Physical lock on machines
- Encrypted data in files
- Firewall if connected to the Internet

Trojan (horse); a program which misleads the user into thinking it is another
piece of software which, when run, executes another program;
Spyware; a program which records data such as usernames and passwords on
a host system and forwards the information to a third party;
Adware; code embedded or attached to program files which will persistently
show adverts (that attempt to generate revenue);
Worm; code which will run autonomously and replicates itself on a host system;
Ransomware; a program that encrypts a user’s data to make it unreadable until
they pay for the key;
Remote Access Tool (RAT); allows access to control and monitor a computer
from a remote network location;
Rootkit; malware that has managed to gain ‘root’ admin privileges;
Bots/Zombies; a program installed on a computer that performs a job for the
remote owner of the bot/zombie such as sending spam or sending web requests
to perform a DOS or attack a computer system;
Scareware; malware that tells you something is wrong with your system in an
attempt to get you to make a purchase;
Keylogger; a program that monitors/records a user’s keystrokes in order to steal
passwords/confidential details

Solid state
 

• Protection against Password-related Vulnerabilities: Traditional password-based authentication methods are vulnerable to various risks, such as weak passwords, password sharing, or password theft.
• Stronger Access Control: Biometric readers add an additional layer of access control to laptops. Even if someone gains physical possession of the laptop, they would still need the authorized user's biometric data to unlock it and access the data. This helps prevent unauthorized individuals from accessing sensitive information stored on the laptop,
• Audit Trail and Accountability: Biometric authentication systems often come with built-in logging and auditing capabilities. This means that each time someone accesses the laptop using their biometric data, it can be recorded and associated with a specific user. This creates an audit trail, allowing organizations to track and monitor access to laptops and establish accountability in case of any security incidents or breaches.

Uses transistors( resistors and capacitors) . It can be implemented by the use of NAND or NOR gates. Data is stored on the chip as a charge

• Resizing using resize handles
• Rotating
• Cropping
• Flipping
• Moving

• Simple technology is needed to develop both hardware and software.
• Digital devices are more reliable, small in size and use less power as compared to analog devices.
• Devices that read, process or output data in digital form are used in computers and other digital devices such as calculators.

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

Multitasking - the  capability of an operating system to enable users to run two or more programs at once on a single computer

Real time processing - data processing system in which the time interval required to process and respond to inputs is so small that the response itself is useful for controlling the physical activity of a process

Time-sharing processing  - a processing mode in which the central processor serves two or more users with different processing requirements (tasks)

On-line processing - is that type of processing where the result of data processing transaction is available immediately

– software that can be used to design new products/amend existing products
– makes use of features such as 2D, 3D, wire frames, library of parts, links to CAM

Give three different applications that make use of CAD.

– aerospace
– architecture
– designing cars
– designing consumer goods
– chemical/nuclear plant design
– designing electronic circuit boards
– ergonomic design
– landscape/garden design

Name three specialist input/output devices used in CAD.

– large monitor/screen with hi-res
– touch screen
– plotter
– space mouse/space ball/4D device
– 3D glasses (in some applications)
– light pen
– graphics tablet
– 3D printer
– 3D scanner

• It transfers data signals from one node directly to another in the network without broadcasting

1. Enable resource sharing
2. Facilitate remote communication
3. Enable distributed processing
4. Provide better data security and management

Without a primary key, a table in a database may have duplicate rows, making data not uniquely identifiable. This can lead to issues with data integrity and challenges in maintaining relationships between tables. Retrieving and updating specific records becomes problematic, and setting referential integrity constraints is impossible, potentially leading to loss of data.

• Unsigned integers store more positive values