Why a Computer Works with Only Two Symbols
Inside the machine every value is a pattern of switches that are either on or off. Two states can be told apart reliably in a circuit, which is the reason a computer counts in twos rather than tens.
What a learner can do afterwards
- Explain why two states are easier for a circuit to keep apart than ten
- Count how many patterns a given number of switches can make, and check that it doubles with each extra switch
- Say what a bit is and what a byte is, without converting any numbers
1 · Read
Every game you play and song you stream on your phone depends on millions of switches turning on and off. Inside the computer, each value is a pattern of on and off switches. Two states are easy to tell apart in a circuit, while ten close levels blur together, so computers count in twos rather than tens.
One switch is called a bit. Eight bits grouped together are called a byte, the chunk that usually stands for one character. Eight switches make 256 patterns. You can use these terms without converting any numbers.
Each extra switch doubles the patterns: one switch makes 2, two make 4, three make 8, four make 16. Doubling each time is the whole trick, so four switches hold 16 patterns.
To count patterns, start at 2 and double for each switch. Never add: three switches give 8, not 6.
Two states survive circuits, each switch doubles the patterns, and eight bits make a byte.
2 · Watch
En anglaisTake it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.