Ch 1 · Why Computers Use Binary · Theory

Topic 1 of 14 in Data Representation — How Computers Store Everything as Numbers — 2 lessons.

Everything Is a Number

A computer has no idea what a letter, a photo, or a song *is*. Underneath, it stores and moves exactly one kind of thing: numbers — and not even ordinary numbers, but numbers written with just two digits, 0 and 1.

Why Only Two Digits?

Inside a computer, everything is built from tiny switches (transistors). A switch is either on or off — there is no reliable "half on". Two clear states are easy to build, fast to read, and hard to confuse with electrical noise.

All topics in Theory Data-representation

  1. Why Computers Use Binary
  2. Counting in Binary
  3. Hexadecimal — Shorthand for Binary
  4. Binary Addition & Overflow
  5. Negative Numbers — Two's Complement
  6. Logical Binary Shifts
  7. Representing Text
  8. Representing Images
  9. Representing Sound
  10. Storage Units & Compression
  11. Floating-Point Numbers (A Level)
  12. More Number Representations
  13. File Organisation & Access (A Level)
  14. Check Your Understanding