How do computers work?
HardwareThe components of a computer are considered hardware; software includes the data that is processed in the hardware. Hardware can again be divided into internal and external hardware, whereby the former are present in the computer case (processor, motherboard, etc.) and the latter can be found outside the cabinet (mouse, screen, etc.). So far some boring definitions that many people already know.
This article first explains the user side: what are programs anyway? How these programs are processed in the computer system is then explained. Finally, the various components and how they are connected are discussed.
Programs and instructionsLet's start with the user. After all, it does not want to do anything other than run programs and use them to process data, such as viewing photos or surfing the internet. Programs consist of instructions. Instructions with computers are actually very simple, for example: "add 4 to 5" or "if variable x is less than 4, go back to the first instruction". In this way, calculations can be made in programs. The program can also choose which part is executed.
In practice, programs are no longer written instruction after instruction. These days, programming languages have been made that are much more convenient to use. The programs made in such programming languages are converted to a file with instructions so that they can be executed.
Von Neumann architecture, the processor and the memoryThe von Neumann architecture describes the essence of how computers work. There is actually one central component, the processor or CPU (Central Processing Unit). On the one hand, it communicates with memory to obtain instructions and save data, and on the other hand, it communicates with peripheral equipment so that, for example, something can be displayed on the screen via a graphic card.
A processor is actually a computer in itself: this chip includes the following important components:
- data path with ALU (Arithmetic Logic Unit), digital logic that performs the actual calculations;
- registers, small and fast memory in which data and instructions can be temporarily stored;
- control unit, retrieves instructions from the memory and passes them on to the data path.
Processors today have become very complex with billions of transistors and smart digital logic, but they still consist of the above components globally.
Memory and storageThe processor also has cache memory: slower and larger memory compared to the registers. Because this memory is installed on-chip, there is little space available. That is why there is still a low memory in many computer systems: this is the RAM (Random Access Memory) or working memory. This memory consists of several memory chips and is placed near the processor.
All the above memory is volatile, when the computer is switched off, the data is lost. That is why hard disks and so-called SSDs (Solid-State Drive) are often used to permanently store data. With hard disks this is done on a magnetic disk (a kind of cassette tape) and with SSDs this is done in transistors that retain their charge.
Graphics CardThe graphic card or video card consists of all kinds of electronics that have direct contact with the processor and aims to generate images that can be displayed on a screen. In the past this was actually not much more than a chip that can convert the digital computer signals into analog signals for the screen. Nowadays these graphic cards can do a lot: they have their own type of processor (the GPU, Graphics Processing Unit) and their own memory. The GPU is capable of performing many simple calculations at the same time and can therefore, for example, draw landscapes for computer games faster than the CPU. The memory is used to store images so that the GPU can get them quickly if needed.
Nowadays, graphic cards are no longer used solely for computer games. The processing of films in high resolutions and the display of web pages are now also performed by graphic cards. Furthermore, graphic cards are also used in the scientific world, think of simulating a human heart.