The world of computer parts can seem baffling to the uninitiated, but there is one component that underlies all other hardware, and its function can be understood at the most basic level: the CPU. The acronym stands for Central Processing Unit, and it’s the electronic machinery that executes instructions from software programs so you can send messages to your friends or play a YouTube video. The CPU is made up of billions of microscopic transistors, which alternate between on and off states, conveying the binary ones and zeroes that represent data in digital form.
The Cpu’s operation breaks down into three key steps: fetch, decode and execute. A CPU reads an instruction from RAM or another source of program memory and stores it in a part of the chip called the instruction register. Then, a circuit known as the instruction decoder converts this machine language into control signals sent to different parts of the CPU for action. The instructions can involve any number of calculations like adding numbers together, performing logical functions, comparing numbers or jumping to a specific part of RAM.
All these operations are done in a sequence, and the processor uses a clock signal to pace these sequential activities. The faster the clock, the more instructions the CPU can perform each second. Once the CPU is done executing an instruction, it may write the results of its work to an internal part of the chip called a cache, which provides very fast access to these numbers and instructions. Alternatively, the results may be written to slower main memory.