Data in Computer Systems

Units

Candidates should be able to:
  • define the terms bit, nibble, byte, kilobyte, megabyte, gigabyte, terabyte
  • understand that data needs to be converted into a binary format to be processed by a computer.

Numbers

Candidates should be able to:
  • convert positive denary whole numbers (0-255) into 8-bit binary numbers and vice versa
  • add two 8-bit binary integers and explain overflow errors which may occur
  • convert positive denary whole numbers (0-255) into 2-digit hexadecimal numbers and vice versa
  • convert between binary and hexadecimal equivalents of the same number
  • explain the use of hexadecimal numbers to represent binary numbers.

Characters

Candidates should be able to:
  • explain the use of binary codes to represent characters
  • explain the term character set
  • describe with examples (for example ASCII and Unicode) the relationship between the number of bits per character in a character set and the number of characters which can be represented.

Images

Candidates should be able to:
  • explain the representation of an image as a series of pixels represented in binary
  • explain the need for metadata to be included in the file such as height, width and colour depth
  • discuss the effect of colour depth and resolution on the size of an image file.

Sound

Candidates should be able to:
  • explain how sound can be sampled and stored in digital form
  • explain how sampling intervals and other considerations affect the size of a sound file and the quality of its playback.

Instructions

Candidates should be able to:
  • explain how instructions are coded as bit patterns
  • explain how the computer distinguishes between instructions and data.

Revision Extras

Memory Units


Colour Depth