CPU performance and embedded systems

• Clock speed: cycles per second, in hertz. 3.2 GHz is 3 200 000 000 cycles a second. A faster clock means more instructions a second, but more heat.
• Cores: each core is a separate processor. Several cores can work on different tasks at once, but a program only speeds up if its work can be split, and cores share memory and cache.
• Cache: the bigger the cache, the more often the CPU finds what it needs there instead of waiting for slower RAM.

time = number of cycles ÷ cycles per second

An embedded system is a computer built into a larger device to do one dedicated job: a washing machine's controller, a thermostat, a car's engine management, a microwave.

• It runs one fixed program, often from ROM.
• It is small, cheap, low-power and reliable because it only needs enough hardware for its task.

A laptop or a phone is general purpose: it runs whatever software the user installs.