Computer processing is an action or series of actions that a microprocessor, also known as a central processing unit (CPU), in a computer performs when it receives information. The CPU is a type of electronic “brain” for a computer system, and it executes a series of instructions that are fed to it by software programs installed onto a computer’s hard drive and loaded into random access memory (RAM). Though modern computer systems have become much faster and more complex than their earlier counterparts, they still perform the same basic type of computer processing.
At their very basic level of function, CPUs are made up of an array of transistors that through a series of binary electrical states of 1s and 0s — or "on" and "off" states — perform mathematical and logical operations that together add up to computer processing capability. The instructions fed to a CPU by a software program alter the states of these transistors to perform calculations for the software program. These results are then usually fed back to RAM memory for use by the software program.
There are four distinct states that processing goes through in order to produce meaningful data output for any program. These states are commonly referred to as fetch, decode, execute and writeback. Fetch is the first state, in which the computer accesses its memory to retrieve instructions, which are always a series of numbers represented by binary code. Binary code is an eight-bit series of digits — strings of 1s and 0s — that together represent one “byte” of data.
After fetching these instructions, computer processing decodes them. That is, the instructions are now broken up into meaningful parts or series of bytes by the CPU’s control unit (CU). These instructions are then executed by the CU.
When the instructions are complex mathematical calculations, the CPU draws on its arithmetic logic unit (ALU) to execute them. In the final computer processing step, a writeback of the data occurs. It is channeled back into computer memory for use by the software program, or it can be stored in memory registers within the CPU itself for later use by the program.
These four processing steps cycle through the CPU continuously, as long as a software program is loaded into memory and is running in the computer itself. These cycles of processing power by CPUs are continuously increasing in speed as computer systems become more advanced, with computers now capable of gigahertz processing cycles. One gigahertz cycle of computer processing is the equivalent of 1 billion instruction sets performed by the CPU every second.