How Does a CPU Work?

By Tiesha Whatley

What is a CPU?

The Central Processing Unit, or CPU, is the brain of a computer. Without this vital component, the computer wouldn’t be able perform any of the functions related to moving and processing data. With each new processor release from manufacturers (primarily AMD and Intel,) CPU become faster and more powerful. Speed and reliability is the name of the game when consumers compare CPU chips in new PCs. For some, the brand of CPU is a major selling point when buying a new computer. For others, raw speed is more important. The faster and more powerful the CPU, the faster the overall system speed.

How Does it Work?

The CPU sits in the motherboard as the central processing unit. All of the other hardware components and programs installed in the system must pass data through the CPU before their functions can be carried out. The CPU’s job function is important and enormous in scale when compared to other components in the system. When a function, program or piece of data is called, the CPU pulls it from Random Access Memory (RAM) and other relevant hardware to process it. The CPU then reads the instructions associated with the task before sending it back to RAM. The instructions that the CPU receives pertain to calculations and data transportation. The system bus is the trail that the data must travel before it is executed. It is the CPU’s job to make sure that the data is guided through the system bus to be processed and then on to the next step. With every stop on the system bus, the CPU makes sure that the data gets there in the correct order.

The Two Data Types

There are two types of data that the CPU handles at a given time. One is the data that needs to be processed. The other is the program code that is connected to the data. The programming code is a list of instructions on how the data should be handled and processed in a language that the CPU can interpret. The programming code also contains the route of the system bus for the data. Since other components of the computer may not understand the programming code, it is the CPU’s job to interpret the instructions for other components in the system. The CPU continues to handle both pieces of data until they are no longer needed - when the program closes or the hardware associated with the task is no longer accessed.

8086 Compatible

Since the CPU must read and interpret data and instructions, the programs and hardware must be compatible for the system to work. Newer CPU chips are able to be "backwards compatible;" they are able to understand components that were present before their conception or release. The concept for this was introduced in 1978 by Intel. Intel's 8086 processor was the first to be capable of this type of "backwards compatibility." All CPUs developed after the 8086 have been designed around this base compatibility architecture.