IGCSE computer science notes (full syllabus)

Computer Science Notes 2018-19

Communication and Internet Technologies
Data Transmission
Security Aspects
Internet Principles Of Operation

Memory And Data Storage
Primary Storage
Random Access Memory
Read Only Memory
Secondary Storage
Magnetic Storage
Offline Storage
Optical Storage
Solid State Storage
File Formats
Musical Instrument Digital Interface
MPEG3 (MP3)
MPEG4 (MP4)
Joint Photographic Expert Group (JPEG)
Lossless compression
Lossy Compression

Operating Systems and Computer Architecture
Operating Systems
Uses/functions
Interrupts
Von Neumann Architecture
The stored program concept
Fetch-Execute Cycle

Input Devices
Two dimensional Scanner
Three dimensional scanner
Barcode Readers
Quick Response Code Readers
Keyboard

, Mouse
Touch Screens
Capacitive
Resistive
Infrared
Interactive Whiteboards
Microphone
Sensors

Output Devices
Inkjet Printers
Thermal Bubble
Piezoelectric
Laser Printers
Three Dimensional (3D) printer
2D cutters
3D cutters
Speakers and headphones
Actuator
Flat panel displays
Liquid Crystal Display
Light emitting diode display
Organic Light Emitting Diode Display (OLED)
Digital Light Projectors
Liquid Crystal Display Projectors

Security
Hacking
Description
Possible effect of the security risk
Methods to remove security risk
Viruses
Description
Possible effect of the security risk
Methods to remove security risk
Phishing
Description
Possible effect of the security risk

, Methods to remove security risk
Pharming
Description
Possible effect of the security risk
Methods to remove security risk
War Driving
Description
Possible effect of the security risk
Methods to remove security risk
Spyware/Key-logging software
Description
Possible effect of the security risk
Methods to remove security risk
Worms
Description
Possible effect of security risk
Loss of data and data corruption
Firewalls
Proxy Servers
Security Protocols
Secure Socket Layer
Transport Layer Security
Encryption
Symmetric Encryption
Asymmetric Encryption
Plain text and Cypher text
Denial of Service Attacks (DoS attacks)

High and low level languages
High Level Languages
Low Level Languages
Assembly code
Translators

, 1 Communication and Internet Technologies

Data Transmission
● Data Transmission is basically the transfer of data from one device or medium to another
device or medium.
● It can either be over short distances or very long distances, three factors have to always
be considered when transmitting data:
○ The direction of data transmission
○ The method of transmission
○ The method of synchronisation between the two devices
● Serial Data Transmission
○ Refers to the process of sending data bit by bit over one single wire or channel
○ This method works very well over long distances however it takes a long time for
data to be fully sent.
○ Eg. Data being sent from a computer to a modem for transmission over a
telephone line.
● Parallel Data Transmission
○ It is when multiple bits of data usually one byte, is sent over several wires
simultaneously, where one wire is used to transmit one bit.
○ This method is faster than serial data transmission however over long distances
the data becomes skewed, i.e. the transmission falls out of synchronisation.
● Simplex data transmission
○ It is when data can only be sent in one direction
○ Eg. when data is sent from a computer to a printer
● Half Duplex Data Transmission
○ It is when data can be sent from one device to another and can be sent back too
however not at the same time.
○ Eg. Walkie Talkies conversations
● Full Duplex Data Transmission
○ It is when data can be sent both direction simultaneously.
○ Eg. Broadband connection over a phone line.
● Asynchronous Data Transmission
○ It refers to data being transmitted in agreed bit patterns.
○ Data bits are grouped together and sent with control bits. These tell the receiver
when the group of data starts and when it finishes.