Computers & Binary (Cambridge International IGCSE Computer Science)

Why Computers Use Binary

Spec point — 1.1.1 · 1 Understand how and why computers use binary to represent all forms of data

Exam Hint This note covers exactly what Cambridge 0478 expects you to know about binary processing—nothing more, nothing less.

Why does data have to be converted to binary to be processed by a computer?

• Data is processed in a computer using logic gates that only have two states
• The binary number system only has two digits (1/0), which means each digit can represent a different state(1 = on, 0 = off)
• All data must be converted to binary before a computer can understand and process it
• Converting data to binary allows computers to process it at an incredible speed, perform complex calculations and store vast amounts of data efficiently

• Secondary storage is a great example of the process

  • Magnetic hard drives use North and South polarity to represent a 1 or a 0
  • In Optical disks, light hitting a flat area (land) is interpreted as a 1 and light hitting a bump (pit) is interpreted as a 0

• Take an example of driving a car

  • When driving a car the accelerator pedal is used to increase the cars speed
  • If a car was accelerating from 50mph to 100mph the increase would be gradual
  • In a computer system, the car is doing either 50mph (0) or 100mph (1), there is no in-between
  • Trying to change the computer system so that it has more options would be less efficient and require more complex parts for the computer to understand

Worked Example Explain why computers process data in binary format [2]

Answer

• Computers process data using logic gates... [1] -... that can only have two states (1/0) [1]

Exam Hint Mark schemes expect: logic gates + two states (1/0). Phrases like “computers understand binary” don’t get the mark, this does.