1.5 How Computers Process and Store Data

Notes

Inside a computer everything is stored as bits, which are 1s and 0s, because electronic parts have two states: on and off.

• A bit is one binary digit. A byte is 8 bits.
• Text, pictures, music and programs are all stored as patterns of bits.
• The CPU repeats the fetch, decode, execute cycle: it gets an instruction from memory, works out what it means, and carries it out.
• The clock speed (measured in GHz) tells how many cycles the CPU can do each second. More cores let a CPU work on several tasks at once.
• Example: a CPU at 3 GHz can do about 3 billion cycles per second.