• It is a feature used to prevent unwanted changes to be made on the data contained in a sheet by limiting the ability to make changes

a repeater will amplify a signal and resend it to overcome reduction in signal strength (attenuation) because over a distance network signals diminish in size/amplitude (are attenuated) due to characteristics of the media.

Prefixing an extra sign bit- A negative number is representes by prefixing a digit 1 to the number

Ones complement- This is flipping the binary equivalent of the number

Twos complement- this involves getting the ones complement and then adding a 1

The organisation of files is in a hierarchy/tree structure
A node is either a folder/directory/sub-folder/sub-directory or the file itself
The top node/folder/directory/drive is the root

A backup is a copy of data that can be used if the original data is lost.

Modulation refers to the process of converting a digital signal to analog signal at the transmission end while demodulation is to converting analog signal to digital signal at the receiving end

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.

• camera film speed, position (end of film), distance, light
• washing machine amount of water, speed of wash/temperature/time
• fridge temperature, display panel
• air conditioning temperature, timing, display pane

• provides an interface between the computer user and the hardware
• Manages the allocation and deallocation of the CPU to processes.
• manages Input-output devices by use of drivers

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

Enrolment:
- Data input on line
- Individual records validated
- Speed mismatch implications
- Indexes updated immediately
Exam grades:
- Data input twice
- Off line
- Run as a batch
- At otherwise downtime

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

1. Virus scanning / Anti-virus. Used to locate and delete viruses / scans and compares files with databases of known viruses.
2. Firewall: checks data packets / examines source address / filters out unexpected packets.
3. Back up. Copies data onto a separate storage device for use if the original data is lost or corrupted.

(The parent can) set criteria for the websites she is allowed to visit such as a whitelist/blacklist of websites. The firewall will examine the data/traffic incoming and outgoing from her computer. If data is sent from a website that is not allowed, it will be blocked

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

• They are small and fit in a small storage space
• They are portable hence can be carried when need to be used outside the office
• Low power consumption
• Have rechargeable batteries

• less errors on input
• requires less storage space
• validation
• quicker to input
• quicker to find

download speed :
– speed at which information/data is transferred FROM server/Internet
– speed at which information/data is transferred TO the user’s computer
upload speed :
– speed at which information/data is transferred FROM user’s computer
– speed at which information/data is transferred TO the Internet/server

CLI

• Commands have to be typed in full with no mistakes
• Requires memorization of commands
• Uses less memory

GUI

• Due to graphics, GUI uses a lot of memory
• GUI is more user friendly
• Cannot operate properly if memory is low

Comparison

• Both carry out file management
• Both are operating systems
• Both control software and hardware

• Network operating systems
• Protocols