Explain why it is not always true that a computer which has a quad-core processor runs twice as fast as a computer with a dual-core processor
State two ways in which data validation is implemented on an input form of a database application
Aeroplanes now use Global Positioning Systems (GPS) to determine their location.
Describe how the computer on board the aeroplane uses GPS to find its exact location
Give two benefits of using GPS in this application
Describe how the computer on board the aeroplane uses GPS to find its exact location
– satellites transmit signals to onboard computers
– computers receive/interpret these signals
– system depends on very accurate timing/use of atomic clocks
– each satellite transmits data indicating location and time
– computer in aeroplane calculates location based on at least three satellites
– at least 24 satellites in operation at any one time
– position accurate to within one metre
– can also calculate altitude of aeroplane
– ref to “triangulation”:
Give two benefits of using GPS in this application
– safer as the known location is exact/more accurate
– reduces the possibility of pilot error
– allows accurate estimation of arrival time
– display and guide the pilot to the nearest airport in case of emergency
Describe the principles of operation of laser printers and describe how they are applied in real-life scenarios
Steps
The data before encryption is known as .................................................. text.
To scramble the data, an encryption .................................................., which is a type
of .................................................., is used.
The data after encryption is known as .................................................. text.
Encryption prevents the data from being .................................................. by a hacker
The data before encryption is known as .......plain.................. text.
To scramble the data, an encryption ......................key.........................., which is a type
of ...................key............................, is used.
The data after encryption is known as ....................cipher............................. text.
Encryption prevents the data from being ......................understood...................... by a hacker
Lucy wrote: “I should validate the input into my database by typing in the same data twice”.Why was her statement incorrect?
Distinguish between an optical scanner and a magnetic ink scanner
State two advantages and one disadvantage of having a network of computers, rather than a series of stand-alone machines, in a school classroom.
Advantages
Disadvantages
Explain why solid state storage is the best choice for a fitness tracker.
OR
OR
State three advantages of biometric authentication
List three characteristics of Internet Protocol version 6 (IP6).
Describe three other different categories of malware.
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 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 attacking 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;
KCSE 2021 Prediction Computer Studies Paper 1 Q.16 (c)
c) Distinguish between a source program and a compiler as used in computer programming. [2]
Source program is the original program in a high level language as written by the programmer while a compiler is a program translator that converts source program to object code.
State advantages of hardcopy output
Describe the query criteria given below
(a) Like "*kenya*"
(b) Like "*ina"
(c) Like U*
(d) Not Like U*
(e) >= "Mexico"
(f) Like "[A-D]*"
(g) "USA" Or "UK"
Describe two health risks associated with the increased use of computers.
Name two other input/output devices used at the POS terminal apart from keyboard and barcode reader and give a use for each device.
device: beeper/loud speaker
use: to indicate barcode correctly read/error in reading barcode
device: (LCD) screen/monitor
use: to show prices and other information about goods
device: touch screen
use: to show prices and other information about goods/to select items that need to be
weighed/identified
device: weighing machine
use: to find weight of loose items (e.g. fruit) to enable pricing
device: (magnetic) card reader/CHIP and PIN reader
use: to read customer’s debit/credit card/enable customer to pay for goods using a
credit or debit card
device: printer
use: to print receipts
Explain, using examples where appropriate, the meaning of these computer terms
(a) byte ..................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(b) compiler ............................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(c) handshaking .....................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(d) technical documentation ..................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(e) simulation .........................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2
(a) byte
(b) compiler program
(c) handshaking
(d) technical documentation
(e) simulation
Describe and give an example of one syntax and one logical programming error.
Syntax
• An error that occurs when a command does not follow the expected syntax of the language, e.g. when a keyword is incorrectly spelt
• Incorrect: IF A ADN B Then
• Correct: IF A AND B Then
Logical
• An error that causes a program to output an incorrect answer (that does not necessarily crash the program)
• An algorithm that calculates a person’s age from their date of birth, but ends up giving negative numbers