Computer Science Paper 2

• hardware

  the physical components which make up a computer system
• software

  the programs which run on a computer system
• system software

  manages the computer system resources and acts as a platform to run application software 
• application software

  software that performs end-user tasks
• low level language

  run directly by processor - no translation needed - little/no abstraction
• low level - advantages

  • easier for a computer to run
  • programs more memory efficient + faster
  • complete control over the CPU
• embedded system - advantages

  • easier to design
  • cheaper to produce
  • overall more efficient
• network disadvantages

  • expensive equipment to set up
  • vulnerable to hacking
  • reliance on the main server - goes down - unable to access files
  • requires a network specialist for maintenance
• pans

  • connect personal devices over a very short range - bluetooth - single user
• lans

  • cover relatively small geographical areas
  • often owned and controlled/managed by a single person or organisation
• wans

  • cover a wide geographic area
  • under collective or distributed ownership
  • internet
• benefits of wired networks

  • stable and reliable connections
  • fast data transmission speed
  • easier to use security measures
  • hard to hack
• disadvantages of wired networks

  • computers only can be used in fixed locations
  • expensive - install hardware
  • specialists required for maintenance
• benefits of wireless networks

  • cheap to set up - do not require cable installation
  • better for environment
  • efficient and easy to add more users
  • convenient - automatic connection and free to move around
• disadvantages of wireless networks

  • lower bandwidth
  • less reliable
  • less stable connections
  • less secure
  • signal strength reduced
• what are the layers of the TCP/IP model?

  • application
  • transport
  • internet
  • link
• what is secondary storage?

  any nonvolatile storage mechanism not directly accessible by the CPU
• what is main memory?

  any form of memory that is directly accessible by the CPU
• how does magnetic storage work?

  binary data is represented by tiny magnetised regions - sectors -tracks - read/write heads

  • magnetic orientation in one direction represents 0, and the other direction represents 1
• how does optical storage work?

  • uses a laser to burn data onto the surface of the disc + also used in order to read the data
  • pits + flat parts represent 0 and 1 (binary data) respectively
• how do solid state drives work?

  • uses electrical circuits to persistently store data
• what are the advantages of optical?

  • cheap per GB
  • portable
  • durable - not damaged by water/shocks
• what are the disadvantages of optical?

  • low capacity
  • poor reliability
  • slow read/write speed
• what are the advantages of magnetic?

  • large capacity
  • portable
  • reliable
  • cheap per GB
• what are the disadvantages of magnetic?

  • not as durable
  • slower access speeds
• what are the advantages of solid state?

  • portable
  • durable
  • reliable over long period
  • fast access speed
• what are the disadvantages of solid state?

  • lower capacity
  • more expensive GB
• what is social engineering?

  the art of manipulating people so they give up confidential information
• what is blagging?

  the act of creating and using an invented scenario to engage a targeted victim in a manner that increases the chance the victim will divulge information or perform actions that would be unlikely in ordinary circumstances
• what is shouldering?

  observing a person's private information over their shoulder
• what is phishing?

  technique of fraudulently obtaining private information, often using email or SMS
• what are relational databases?

  made up of multiple tables linked together by using primary and foreign keys
• what is a foreign key?

  field that references the primary key of another table - creates a link
• what are the advantages of a relational database?

  • eliminates data redundancy
  • reduces data inconsistency
  • reduces storage space
• what is a primary key?

  field which can uniquely identify any record in table
• what are the command words for sql?

  SELECT, FROM, WHERE, ORDER BY
• what is the purpose of *?

  wildcard - returns all the fields