Computer science (Paper 1)

Computer science (Paper 1)

1. Processor and Fetch Execute cycle

2. RAM and ROM

   • RAM
     • Random Access Memory
     • volatile
     • Memory is lost when no power is supplied
     • Moves to virtual memory upon overflow
   • ROM
     • Read Only Memory
     • non-volatile
     • stores content after use
     • stores software that boots the computer

3. Computer Parts

   • CPU
   • Accumulator
   • Arithmetic logic unit

4. Storage Methods

   • Solid state
     • SSD
       • Use flash Memory to save and store data
         • Retains memory when no power is supplied
         • Portable
       • Solid State Devices
       • Memory sticks
       • Less prone to error than magnetic disks
       • sometimes faster than magnetic disks
       • use USB
       • No moving parts
   • Optical
     • Physical rather than virtual
     • Computer system burns 'pits' into the disk surface
       • each pit reflects light differently
     • DVD-ROM
     • DVD-R
     • DVD-RW
     • DVD-RAM
     • CD-ROM
   • Magnetic
     • use magnetic fields to save data
     • disk is given a positive or negative charge
     • hard drives
     • floppy disks
     • magnetic tapes

5. Networks

   • Topologies
   • Protocols
     • HTTP
       • Hypertext transfer protocol
       • foundation of data communication on the web
       • it is used for distributed, hypermedia information and collaborative systems
       • uses hyperlinks
     • MTP
       • Media transfer protocol
       • is an extension of picture transfer protocol
         • was designed for downloading photographs from digital cameras
       • allows media to be transferred to and from portable devices
       • allows the transfer of music files on digital audio players and media files on portable media players
   • Types of network
     • LAN
       • Local area Network
       • is located in one site
       • only owned by one organisation
         • organisation usually owns all hardware
       • users are required to be in the LAN to access its services
       • an reach across multiple buildings
     • WAN
       • Wide Area Network
       • when a LAN connects to other LANs
     • VPN
     • Wired
     • Wireless
   • Server types
     • Database server
     • Web server
     • Print server
     • File server

6. Ethics and Legal

   • ethics
   • legal
     • Data protection act, 1998
       • gives rights to data subjects
       • before use organisations must register to the act
       • 8 principles
         • data must only be used in a fair and lawful way
         • data must only be used for specified purposes
         • data must be adequate, relevant and not excessive for the specified purpose
         • data must be accurate and kept up to date
         • data should not be kept longer than necessary
         • the rights of the data subject must be observed
         • data should be safe and secure
         • data should not be transferred abroad without adequate protection
     • Freedom of information act, 2000
       • allows members of the public to access information held by a public organisation regarding activities
       • Gov. depts.
       • Houses of P
       • Councils
       • Armed forces
       • Information can be withheld if intended for future publication
       • police
       • Schools
       • Universities
     • Computer misuse act, 1990
       • prevents hacking and cybercrime
       • introduced three new offences
         • gaining unauthorised access to a private network or device
         • Gaining unauthorised access in order to commit a crime such as theft or network damage/ destruction
         • unauthorised modification of computer material
     • Copyrights, designs and patents act, 1988
       • protects intellectual property
       • copyright protects

7. DNS

   • Domain name server
     • Translates domain name to an IP address

8. E-Mail Protocols

   • IMAP
   • POP
   • SMTP

9. Viruses and Malware

   • Network attacks
     • passive attacks
       • someone monitors data in a network and intercepts any sensitive information found
       • uses network monitoring hardware and software
         • packet sniffers
       • best defence is data encryption
     • active attacks
       • someone attacks the network with malware or other planned attacks
       • the best protection is to have a firewall
     • insider attacks
       • someone in an organisation exploiting the network's access to steal information
     • brute force attacks
       • trial and error
       • gains passwords by trying different combinations
       • uses predictable passes such as real words and predictable number sequences
       • best defence is having your account lock after so many attempts
     • denial-of-service attacks
       • hackers try to stop users accessing part of a network or website
       • involves flooding the network with requests and useless traffic
         • makes the network extremely slow or inaccessible

10. Operating Systems

11. Utility Programs

12. Writing Algorithms

13. 00010111

    • 256-128-64-32-16-8-4-2-1
      • 32 + 4 + 2 +1 = 39
        • 1E