1. CXC Information Technology
Section One Revision
Does not include binary arithmetic & Information Processing (Unit 5)
What you’ll need
Past paper questions: 2010 – 2014
Mr. Alleyne website:
Constant revision is critical

2. Unit One - Basic components
CPU: ALU and control unit
Primary Storage: RAM, ROM etc.
Secondary Storage: diskettes, CDs etc.
Input devices: mouse etc.
Output devices: monitor etc.

3. Primary Memory
Bistable device: Only has two states, on and off (1 and 0)
Read Only Memory: boots up the PC. Non volatile
Random Access Memory: used while PC is working. Volatile (needs power)
PROM: Programmable ROM
EPROM: Erasable programmable ROM

4. Secondary memory
Magnetic tape: uses sequential access. Good for backing up
Floppy disk: uses direct access.
Hard disk (drive): fixed or moving head
Optical disk: CD / DVD
Memory cards: Cameras, phones etc.
USB (flash) drives: Portable
USB – Universal Serial Bus

5. Other terms Track: Circles around disk’s surface
Sector: One part of the circle
Cluster: Adjacent sectors
Buffer: extra memory space when copying data
Sequential access: data stored in the order it’s received
Direct access: data stored in any order
Hard drive interfaces
SCSI, IDE, SATA and USB (external hard drive)

6. Units of storage Bit: smallest unit of storage Byte: 8 bits
Kilobyte: 1024 bytes
Megabyte: 1024 kilobytes
Gigabyte: 1024 megabytes
Terabyte: 1024 gigabytes
Word / Word size: size of a single instruction. (i.e. How much data a CPU can handle at one time.)

7. Input Devices Mouse Keyboard Joystick Microphone Scanner Webcam
Graphics pad/tablet
Barcode reader
Light Pen
Touch terminal
Optical Mark Reader
Optical Character Reader
Magnetic Ink Character Reader
Biometric System
Sensor

8. Output Devices Monitor Projector Speakers Headphones Printers Plotter
Microfilm

9. Output terms Resolution Pixel Quality Hard copy Soft copy
Human readable
Machine readable

10. Printers Dot matrix Line IMPACT Daisy Wheel Inkjet Laserjet Thermal
NON -IMPACT

11. Software Application Software Systems software
Custom written (for one purpose only)
Specialised (for a group/category: ACCPAC)
General purpose (for everyone: Word, etc.)
Integrated (more than one programme: Office)
Systems software
Operating system (Windows, Linux, Unix, OSX)

12. Operating System functions
File management
Resource management
User management
Input – Output management
Security
Memory
Maintenance (defrag, format, cleanup)

13. Interfaces and terms
Command line interface: command must be typed. Difficult to use
Menu driven interface: command selected from a menu: Options limited
Graphical user interface: Like Windows
Pop up and pull down menus
Icons
Taskbar

14. Processing – how does the CPU do it?
Batch: collect in groups, then process
Online: processed once CPU is on
Real-time: processed immediately
Timesharing: processes many jobs, a piece at a time

15. Computer specifications
CPU: 2.4 Ghz 64-bit Pentium 4
Hard drive: 1TB 7200 rpm SATA
Memory: 1GB DDR-RAM
OS: Windows 7 Home edition
Ports: 6 USB ports, 1 firewire port
Optical drive: 54X DVD/RW drive
Slots: 1 AGP slot
Video: Radeon 64MB video card

16. Extranet: private with some outside access
Networks
Local area network: small area
Metropolitan area network: medium sized area
Wide area network: large area (e.g. continent)
Internet: public
Intranet: private
Extranet: private with some outside access

17. Networking terms Coaxial cable (antenna) Bandwidth (how much)
Twisted pair (phone/ADSL)
Fiber optic cable (light)
Infrared
Bluetooth
Wi-fi
Hotspot
Bandwidth (how much)
Speed / Rate (how fast)
Voiceband (phone line)
Broadband (ADSL)
Wireless
Simplex (1 way only)
Half duplex (1 way at a time)
Full duplex (both ways)

18. The internet & terms WWW Web page, site, browser HTTP, HTML FTP URL
Upload vs. download
Search engine
IRC
Bulletin board
Newsgroup
Blogging
E-commerce
E- learning
VoIP

19. Data Security Passwords Encryption Access restrictions Firewalls
Virus protection
Backup & recovery
Archiving
Locks
Security guards
Fireproof cabinets
Waterproof cabinets
Biometric systems

20. Data misuse Information Theft Copyright infringement Eavesdropping
Invasion of privacy
Computer fraud
Propaganda

21. Current trends Expert Systems
Computer Aided Manufacturing (and Design)
Teleconferencing
Telemarketing
Robots
Laser technology

22. Jobs Technician Software / computer engineer
Database / Network administrator
File librarian
Web master / web developer
Software trainer (teacher)
Systems analyst
Programmers

23. Information Processing
Anyone can use computers for the following
Communication
Research
Publishing and Printing
Storage
Data processing and analysis