Exam (elaborations)

CAMBRIDGE IGCSE COMPUTER SCIENCE EXAMS QUESTIONS AND ANSWERS

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Cambridge IGCSE Computer Science

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Cambridge IGCSE Computer Science

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Uploaded on October 19, 2024
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Written in 2024/2025
Type Exam (elaborations)
Contains Questions & answers

web browser
actuator
loudspeaker
ccfl
cambridge igcse computer science
http hypertext transfer protocol
url uniform resource locator

Institution Cambridge IGCSE Computer Science
Module Cambridge IGCSE Computer Science

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Cambridge IGCSE Computer Science
HTTP - hypertext transfer protocol - Answer- a set of rules which must be followed when transferring files across the
internet

URL - uniform resource locator - Answer- used to find/identify a webpage on the internet 1. webserver name 2. file name
3. protocol

web browser - Answer- software that allows a user to display a webpage on their screen - they interpret html code and
show the result

actuator - Answer- used in many control operations involving sensors and ADC/DACs. Electromagnetic device eg. motor
that outputs result of sensor operation

loudspeaker - Answer- output device that produces sound using voltages at different levels which vibrate a cone in
speaker housing

LED - Answer- Used for backlighting a monitor/tv - they are thin, produce a white light, and do not require much power

CCFL - Answer- Old technology used for backlighting - took time to warm up, and produced yellow-ish lighting + required
a lot of power

volatile - Answer- memory that loses its contents when the power is off eg. main memory

non-volatile - Answer- memory that doesn't lose its contents when the power is off e.g. hard disk

off-line storage - Answer- storage that can be physically moved away from a device and stored somewhere else e.g. CD,
USB stick, DVD

SRAM - Answer- type of RAM that has 'flip flops' to hold each bit of memory. Does not need constant refreshing.

magnetic media - Answer- secondary storage with mechanical parts which move over the surface to read and write data
magnetically e.g. a hard disk, tape or floppy disk

program - Answer- our way of telling a computer what to do, how to do it, and when to do it

assembly language - Answer- code that is specific to a particular hardware, but needs to be translated into machine code
before it can run

machine code - Answer- the binary code that is specific to a machine and does not need translating in order to run

translator - Answer- program that changes higher level language into machine code

compiler - Answer- this translates HLL into machine code. Once it has done this, the program can be used multiple times
without translating it again

UPS - Answer- uninterruptable power supply

cracking - Answer- editing source code with malicious intent

firewall - Answer- this examines traffic between a user's computer and the internet by checking what is/isn't allowed and
blocking traffic that does not meet certain criteria

proxy server - Answer- this filters web traffic, keeps the IP address secret, and, using a cache, speeds up access to
websites that have been visited before

TLS - Transport Layer Security - Answer- this is a form of secure data transmission made up of 2 layers: the record
protocol, and the handshaking protocol. It is very secure and fairly new, and can make use of session caching, which
improves performance. It involves many complicated encryption algorithms. prevents third party hacking into communication
between web server and the user's computer.

,session caching - Answer- this is used in TLS to avoid using too much computer time; TLS is able to attempt to resume
an existing session, which increases speed.

Denial of Service (DoS) attack - Answer- attempting to prevent a user from accessing part of a network (usually the
server); this is usually temporary, but may be very damaging, or a big security breach. overloads web traffic by sending
thousands of requests.

free software - Answer- software that is free to run, copy, change or adapt, and share with friends, family or colleagues.

CSS - Answer- Cascading Style Sheet. Controls presentation of page. Enable multiple pages or elements on a page to be
changed in one go.

Gigabyte (GB) - Answer- 1024 megabytes. 2 to the power of 30 bytes.

HTML - Answer- HyperText Mark-up Language. Used to write and develop webpages to present text. Uses tags.

Terabyte (TB) - Answer- 1024 gigabytes. 2 to the power of 40 bytes.

Lossless image compression - Answer- Find groups of repeating data. Records the data once and the number of times it
was repeated.

Lossless text compression - Answer- Finds patterns in original text. Encodes each pattern in a dictionary

PNG - Answer- Lossless picture file format that uses alpha channel to keep transparent backgrounds.

MIDI - Answer- A set of instructions for digital instruments to play synthesised sounds. Musical Instrument Digital
Interface.

.WAV - Answer- uncompressed music files

.FLAC - Answer- lossless compressed music files

Parity bit - Answer- Set to 1 or 0. Sent with a byte of data to make the total number of 1s odd or even for each byte.

1KB (kilobyte) - Answer- 1,024 bytes (2¹⁰ bits)

1MB (megabyte) - Answer- (2²⁰ bits)

1GB (gigabyte) - Answer- (2³⁰ bits)

1TB (terabyte) - Answer- (2⁴⁰ bits)

1PB (petabyte) - Answer- (2⁵⁰ bits)

A - Answer- 10

B - Answer- 11

C - Answer- 12

D - Answer- 13

E - Answer- 14

F - Answer- 15

Simplex - Answer- Data sent in 1 direction only

Asynchronous - Answer- Agreed bit pattern with control bits

Parity Check - Answer- Uses parity bits. Odd Parity / Even Parity agreed between sender and receiver. If it is not the
agreed number, an error has occurred.

ARQ (Automatic Repeat Request) - Answer- Uses acknowledgement and timeout. If acknowledgement isn't sent back to
sender before the timeout occurs, message automatically resent.

, Checksum - Answer- Additional value sent at the end of a data block. When block is about to be transmitted, additional
value calculated and then transmitted. Value recalculated at the end to make sure they match. If they don't match, an error
has occurred.

Echo Check - Answer- Data sent to and from another device twice. Sender compares 2 sets of data, if the sets of data are
different, an error has occurred.

Wardriving - Answer- Using wireless internet connections illegally through a portable device

Secure Sockets Layer (SSL) - Answer- When a user logs onto a website, it encrypts the data. Only the user's computer +
web server can make sense of what's being said. A green padlock in the status bar.

Record Protocol - Answer- Can be used with or without encryption

Handshake Protocol - Answer- Permits the website and user to authenticate and make use of encryption algorithms which
only the user and website know.

Encryption - Answer- Makes data meaningless unless recipient has the decryption key

Asymmetric Encryption - Answer- Private and public key are both needed. Encryption keys generated using a hashing
algorithm.

Authentication - Answer- Used to verify data is coming from a trusted source.

MAC address - Answer- a number that uniquely identifies a device on the Internet. Often refers to network card. Rarely
changed.

ISP (internet service provider) - Answer- company charging monthly fee that provides internet access

IP (internet protocol) address - Answer- assigned by ISP, unique to each internet session

MAC address - Answer- number which uniquely identifies a device - 1st half = manufacturer, 2nd = device itself - made up
of 6 groups of hex digits

HTML Presentation - Answer- how the document looks/sounds

HTTPS - Answer- a SECURE set of rules which must be followed when transferring files across the internet

OLED - Answer- new technology used for tv/monitor screens, using a cathode and anode. Flexible, no backlighting
required.

DLP - Answer- light projector using mirrors to produce 1024 different grey shades. A bright white light source passed
through colour filter allowing 16million colours to be created.

ROM - Answer- memory that is hard coded at time of manufacture. Stores start-up programs, bios and BOOTSTRAP

secondary memory/storage - Answer- long-term, non volatile storage media e.g. hard disk

virtual memory - Answer- part of the hard disk that is programmed to work as an extension of main memory

DRAM - Answer- type of RAM where each chip consists of transistors and capacitors. Not too expensive to manufacture,
has high storage capacity, and doesn't consume too much power. Needs refreshing every 15s

SRAM - Answer- type of RAM that has 'flip flops' to hold each bit of memory. Does not need constant refreshing.

bootstrap - Answer- the first program loaded from ROM by BIOS; loads operating system from secondary storage

optical media - Answer- secondary storage that is read using lasers e.g. CD, DVD

solid state/flash memory - Answer- secondary storage with no moving parts; used in memory sticks, cameras and phones

FAT - file allocation table - Answer- a map of where each file is and which sectors on the magnetic disk are free

high level language - Answer- portable language designed with the programmer in mind - it is easy to understand and
debug, but it needs to be translated in order for a computer to understand it

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Exam (elaborations)

CAMBRIDGE IGCSE COMPUTER SCIENCE EXAMS QUESTIONS AND ANSWERS

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