Computer Systems

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.

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

Describe the environmental impact of intelligent systems:

• heating systems

• traffic control

• car management systems

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