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F01

What Is a Computer?

“A computer is a giant room of light switches”

Lessons

Start the course →0 of 7 lessons done
  1. A room full of light switchesEvery computer is built from tiny on/off switches called bits. Each extra switch doubles what you can say. · 8 min
  2. Counting with switchesBinary numbers give each switch a value (1, 2, 4, 8…). Add up the switches that are on to get the number. · 10 min
  3. Turning letters into numbersText is stored by giving every character a number (A = 65), then storing that number in binary. That shared list is called Unicode. · 9 min
  4. Hexadecimal and byte sizesLong rows of 0s and 1s are hard to read, so programmers write each group of 4 bits as one hexadecimal digit (0–9, then A–F). And bytes add up into KB, MB and GB. · 10 min
  5. Pictures as numbersA digital picture is a grid of tiny colored squares called pixels. Each pixel's color is three numbers, how much red, green and blue light to mix. · 10 min
  6. Sound and video as numbersSound is a wave. Computers measure its height thousands of times a second and store each measurement as a number. Video is a fast flipbook of pictures plus sound. · 10 min
  7. Logic gatesA logic gate is a tiny circuit that looks at on/off inputs and produces an on/off output by a simple rule (AND, OR, NOT). Every computer is built from billions of them. · 12 min

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