GCSE Computing/Representation of Data in Computer Systems

Section 2.1.4 Representation of data in computer systems

Topics

Units

• (a) Define the terms

• bit,
• nibble,
• byte,
• kilobyte,
• megabyte,
• gigabyte,
• terabyte.

(b) understand that data needs to be converted into a binary format to be processed by a computer.

• (c) Convert positive denary whole numbers (0-255) into 8-bit binary numbers and vice versa
• (d) Add two 8-bit binary integers and explain overflow errors which may occur
• (e) convert positive denary whole numbers (0-255) into 2-digit hexadecimal numbers and vice versa
• (f) convert between binary and hexadecimal equivalents of the same number
• (g) explain the use of hexadecimal numbers to represent binary numbers.

Character

Candidates should be able to:

• (h) explain the use of binary codes to represent characters
• (i) explain the term character set
• (j) 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:

• (k) explain the representation of an image as a series of pixels represented in binary
• (l) explain the need for metadata to be included in the file such as height, width and colour depth
• (m) discuss the effect of colour depth and resolution on the size of an image file.

Sound

Candidates should be able to:

• (n) explain how sound can be sampled and stored in digital form
• (o) explain how sampling intervals and other considerations affect the size of a sound file and

the quality of its playback.

Instructions

(p) explain how instructions are coded as bit patterns (q) explain how the computer distinguishes between instructions and data