Computers represent all data using binary.
Explain one reason why computers use binary to represent data.
Mark scheme
Award up to two marks for a linked explanation such as:
- (Computers) are made of electronic components/switches/transistors that have two states, on/off (1) so binary's two values 0 and 1 can represent these states (1)
- Data stored as binary is more resistant to errors (1) because only two voltage levels/states need to be distinguished, so electrical noise/interference is less likely to be misread as a different value (1)
- Circuits that only need to distinguish two states are simpler/cheaper to manufacture (1) because each component only needs to hold one of two stable states (1)
For both marks, the expansion must follow/associate with the statement.
Do not accept 'computers only understand 0s and 1s' as a reason on its own without saying what the two states are or why binary matches them.
Do not accept 'computers are digital' or 'that is how computers work' without expansion.
Do not accept 'binary is easier to read/write' or 'binary is easier to understand' as a reason for using binary.
Do not award the same point twice if it is repeated in different words, e.g. two answers that both say circuits/components are on or off.
Example answers and how they were marked
Computers use binary because their electronic circuits have two states, on and off. Binary also has only two values, 0 and 1, so these can represent the states of the circuit.
Why: Links the two circuit states (1) to binary's two values representing them (1).
Computers use binary because their circuits are either on or off.
Why: Identifies the two circuit states (1) but does not link them to binary's two values, so the second mark is not awarded.
Computers use binary because it is easier to read than denary.
Why: 'Easier to read' is a reason for using hexadecimal, not a correct reason for using binary; the mark scheme tells markers not to accept it, so no mark.