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Computer bus: What is it, what is it for and how are they classified in computing?

Computer bus: What is it

There is no more noticeable work of electronic and computer engineers than the development of different buses. Thanks to the development of this kind of architecture, today we can have in our hands, mobiles and computers with very large and at the same time simple memory capabilities with almost instantaneous functions.

A mobile device, on its circuit boards, really presents extraordinary bus designs , making them true tools that we cannot miss today.

In this article we are going to explain what are the buses in computer science and we will also detail the different classes that exist of each one of them and their different functions. We will also talk about the evolution that these buses had and that are reflected in their different generations.

What is a bus and what is its usefulness in computing?

Qué es un bus y cuál es su utilidad dentro de la informática

The computer bus is the system by which the different components that a computer has transfer and relate the data they share to each other.

This is done thanks to a circuit that is printed on different boards and is made up of wires or tracks, resistors (which are responsible for introducing electrical resistance to certain parts of the circuit) and capacitors (responsible for functioning as an energy storage that these circuits need).

There are two types of data transfer in the computer architecture. One is the serial transfer that can carry one bit at a time. The other kind of transfer is the parallel call which can transfer up to 8 bits at a time.

Channels are currently used to transport several buses at the same time, the most commonly used being the serial ones. We will develop this topic more deeply in the last part of this article.

Thanks to the existence of these computer buses, we can get the microprocessor to communicate with the memory; and also the input ports , such as the keyboard, mouse and microphone; and the output ports, such as the monitor, the printer or the speakers with the different parts of the operating system .

How does a computer bus work? Components and features

¿Cómo funciona un bus informático? Componentes y características

The operation basically consists of passing electrical signals through metallic conductors and being received by another component according to integrated protocols that they handle together.

They can also conduct digitized signals and define their capacity according to the number of repetitions they can perform in a specific time, classified by the sending of that frequency and the width of the data. This relationship is inversely proportional to each other.

The components that a bus has are:

  • Cables , which is used to transmit electricity.
  • Board, that has a circuit of roads, tracks and others printed on it elements with materials that are conductive or not of electricity. Its mission is to drive and deliver data between the components.
  • Resistors as we had named, they are electronic components that are designed to work as resistance, that is, analyze the transmission that exists between two points of the electrical frequency, generating a control of the maximum current that passes through it.
  • Capacitors, work to be able to store energy and at the same time transmit it to different elements that need so immediate electricity. Your work is passive.

What are the main generations of buses that exist?

There are different generations of buses that were modified through the discovery and development of better transfers through the channels.

Next, we will name each of the generations that exist:

First generation

This generation takes place between the decades of ´70 and ´80 where there were two buses, not destined for memory and the other bus was destined for the different devices that surrounded the memory .

That is, with this generation the computer worked with two defined areas and with specific instructions and synchronizations for each of them.

Second generation

This stage is characterized by the greater speed and autonomy of the buses. The most important problem this passive bus generation class had was that it needed to use the CPU to control the buses, which meant an important part of it.

The hierarchy between the different buses began to be established according to the degree of frequency. It takes place between the 90s and the beginning of this century .

Third generation

It is the generation that is currently used and its most important feature is that it allows point-to-point connections, managing to fragment the routes or tracks where the data travel, thus reducing the number of connections and achieving interfaces serially .

It is a relatively new technology, it has 10 years in the computer market .

How are computer buses classified? All types

Next, we will talk about how these computer buses are classified according to their functions:

Parallel bus

As we said before, a parallel bus is one that is dedicated to transmit the data one byte at a time and at the same time. It is characterized by a frequency that is small but has a large amount of data sent.

Its connections are complex and the logic it maintains is simple is widely used for those systems where little data or computing power is needed.

These were the most used between the first and second generation, but they had disadvantages in terms of the control that had to exist from the CPU.

Serial bus

We also talked about it before, a serial bus is one that is characterized by being able to transmit up to bit at the same time. Your bandwidth will depend on the frequency where they are broadcast since they are inversely proportional.

They are currently used especially for hard drives in solid state because they allow for greater efficiency in the transmission of information.


Control buses are an integral part of parallel buses and are responsible for transmitting all data or signals so that you can control the devices that need to communicate.

They are widely used in status indicators, since they can govern each of the components that have connections or lines shared with each other.


Which can be shifted in a random way so you need a power so you can have data exchange directly with the CPU. You can control the data bus and the address bus for its use and access.


An address bus is one that can have a number to assign to a memory or memory cell within the main memory such as RAM.

It is independent of the data bus and can work directly with the microprocessor through a channel assigned for that purpose.


This class of buses is responsible for being able to transmit electricity sometimes to an address bus and other times to data buses with the characteristic that they never do so at the same time.

The chipset What is your relationship with the computer buses?

El chipset ¿Qué relación tiene con los buses informáticos?

The Chipset is the set of integrated circuits that is hosted on the motherboard or “motherboard” and its main function is to collect the data of all processes and send them to their correct recipient .

It is the one that controls different hardware functions and access to memory, among other functions. That is, it makes the motherboard connect to the most important components that our PC has, making the motherboard the main protagonist of the entire hardware operating system of our equipment.

From here we can conclude that the chipset is closely related to computer buses since without them there could be no communication to collect and send the processes.

In addition, the chipset is also designed with a computer architecture using different buses to connect between its internal components .