Topic

Computer Systems (CS) – Higher (v2.1)

Data representation

 Describe and exemplify the use of binary to represent positive and negative integers using two’s complement, including the range of numbers that can be represented using a fixed number of bits.

Conversion of two’s complement numbers from binary to denary and vice versa.

Describe and exemplify floating-point representation of positive and negative real numbers, using the terms mantissa and exponent.

Describe the relationship between the number of bits assigned to the mantissa/exponent, and the range and precision of floating-point numbers.

Describe Unicode used to represent characters and its advantage over extended ASCII code (8-bit) in terms of numbers of characters.

Describe the relative advantages and disadvantages of bit-mapped graphics versus vector graphics.

Computer structure

 Describe the concept of the fetch-execute cycle.

Describe the factors affecting computer system performance:

  • number of processors (cores)
  • width of data bus
  • cache memory
  • clock speed

Environmental impact

 Describe the environmental impact of intelligent systems:

  • heating systems
  • traffic control
  • car management systems

Security risks and precautions

 Describe and identify the implications for individuals and businesses of the Computer Misuse Act 1990:

  • unauthorised access to computer material
  • unauthorised access with intent to commit a further offence
  • unauthorised modification of programs or data on a computer

Describe and identify the security risks of:

  • tracking cookies
  • DOS (Denial of Service) attacks:
    • symptoms
      • slow performance, inability to access
    • effects
      • disruption to users and businesses
    • costs
      • lost revenue, labour in rectifying fault
    • type of fault
      • bandwidth consumption, resource starvation, Domain Name Service (DNS)
    • reasons
      • financial, political, personal

Describe how encryption is used to secure transmission of data:

  • use of public and private keys
  • digital certificates
  • digital signatures