Usb: what it is, types, formats and speeds 【complete guide】 ⚡✔️

The USB, Universal Serial Bus for lawyers, is the cool kid on the playground today. Practically all electronic devices have something to do with it and that is that in the end we use it for almost everything. Keyboards, mice, external memories, headphones, joysticks etc. Today we are going to review a very quick history of where this beauty came from, its formats, speeds and more. Let's start!

Index of contents

A little context

In 1996 USB was born as a result of the collaboration of computer designer Ajay V. Bhatt and Intel Corporation. This bus transmits information between the computer and other peripherals connected to it, later expanding to almost any other existing device. What caused this type of port to bomb and rise above the rest was its ability to serve as a connection for a vast number of devices.

By becoming a standardized connector, USB is now a must-have for manufacturers of all types of products, and its speeds and port sizes have had to adapt to the times. Its versatility made unnecessary ports that previously had unquestionable uses, such as the PS / 2 of older keyboards and mice.

How a USB works

Well, before we get into an eleven-rod shirt, let's start with the basics. We assure you that here we will try to reduce technicalities to a minimum and maintain an understandable language for all audiences, do not panic!

USB cable

To explain this section we will make a distinction between the USB cable and what comes to be the port itself. A device connected by USB via cable contains two internal ramifications. They are known as twisted pair cable . In this type of connectors the voltage is 5 volts and what can vary is its intensity (amperage) depending on the version as well as other differences in its manufacture:

• USB 1.0 to 2.0: The two cables can both send and receive, but not at the same time. It is what we know as half duplex . Its output intensity is 500 mAh. USB 3.0 onwards: the number of cables is increased to four and this allows data to be sent and received simultaneously: two for each function. This would be full duplex . Its intensity is 900 mAh.

USB port

Within the connector we will find that there are differences in the number of pins and format of the contacts that vary depending on their size and the USB version. We will explain this in depth in the section "USB port formats" after having broken down its functions.

Once we connect a USB to our computer, television or tablet, the system identifies the device and (if needed) allows it to be "installed" looking for the most suitable driver for its profile (this occurs when we connect elements such as a mouse for the first time, printer or pendrive ). In the rare case that this is not the case, it is up to the user to search for and manually install the drivers they need. This is how this type of connection format is created, generating a fast and dynamic transfer of information that does not require turning off the computer.

USB versions

Prototypes in development

Like all products, the USB had a pre-launch testing and prototyping phase that consisted of a development process until we reached version 1.0, which was finally released in 1996. These versions that we never used were:

• USB 0.7 : released in November 1994. USB 0.8 : released in December 1994. USB 0.9 : released in April 1995. USB 0.99 : released in August 1996.

We can say that these were his "pre-alpha prototypes" and led the team to the final version that we all know.

USB on the market

USB 1.0, 1996

Far from what we all might think today given that many in the 90's would not have noticed the difference, USB was not that it was welcomed with open arms when it hit the market. With a maximum transfer rate of 1.5Mbit / s (about 188 kB / s), this first model was slower than the bad horse. Despite its lukewarm beginnings, this port was mainly used for everyday devices such as keyboards, mice, webcams or USB sticks . Despite its speed, this introduction made the general public familiar with its use and paved the way for what was to come.

USB 1.1, 1998

The version that really sparked the issue and started the race to USB glory. A tenth may not seem like a lot of difference to the naked eye, but I already told you that the differences were remarkable. The transfer speed went from 1.5Mbit / s to 12Mbit / s. As you can imagine USB 1.1 looked like a Formula One next to its predecessor and quickly gained strength. Its uses continued to diversify thanks to the acquired popularity. USB settled firmly on the market.

USB 2.0, 2000

Here came the fighter jet, high speed with capital letters, although it is an aspect that will not stop in this version. From 12Mbit / s we go to 480Mbit / s. This is about 60 megabytes per second under optimal conditions, although it was somewhat cheating. Normally we would find that its real rate used to be around 280Mbit / s.

USB 2.0 is here to stay with us for a long time, and this is mainly due to the digital age of the new century. The 1080p Full HD image resolution caused the films, series or photographs to become heavier each time, so it was necessary to increase the transfer speed of multimedia devices, hence the speed increase almost forty times compared to 1.1.

USB 3.0, 2009

It took nine years for a new version to appear on the market. If USB 2.0 already seemed fast to us as a fighter, 3.0 is directly a space rocket. With a transfer rate of up to 4.8 Gbit / s (600 MB / s), this bug took to the streets at 2.0. The introduction of this port coexists in most laptops, desktops, USB sticks and external hard drives, although it is also possible to find it in products such as motherboards.

We recommend reading: USB 3.0 vs. USB 3.1 - The most important differences.

Normally we can distinguish it in its standard size because the internal tab of the connector port is usually blue and not black. Within version 3.0 and until the appearance of USB 4.0 we find two later variants known as SuperSpeed ​​or Super Speed:

• USB 3.1 SuperSpeed, 2013: Transfer rate increases from 4.8 Gbit / s (600 MB / s) to 10 Gbit / s (1.25 GB / s). USB 3.2 SuperSpeed, 2019: We are in 2019, but although USB 3.2 has been announced for the end of the year, it has not yet been officially launched. It is expected that it will reach a transfer rate of up to 20 Gbit / s (2.5 GB / s) and that we can find compatible components, peripherals and computers by 2020.

Related to this section you may be interested: USB 3.1 Gen 1 vs USB 3.1 Gen 2 All the differences between USB ports.

Port formats

Okay, now that we know about versions, let's look at the types of ports. Here we have a situation similar to that of HDMI. The slim formats force to get connectors with increasingly reduced designs to connect cables to mobile devices, cameras, laptops, tablets and others. USBs are not left out of this league and as there is always a broken for a rip, these are their formats:

Image: wikimedia commons

USB type A

Type A connectors are the model that connects directly to the CPU. Within this category we can find the following sizes:

Standard USB A

The one of a lifetime, you know which one I'm talking about. All USB sticks , mice, keyboards, televisions and hard drives use them followed by a long list of other devices. We have them more seen than the comic.

• A USB type A is characterized by having a tab (black as a general rule, blue for versions 3.0) that prevents us from connecting them backwards. The contact of its four pins is in a horizontal line.

Standard USB 3.0 Type A

USB 3.0 by default shares all the structural characteristics of the standard type A port used by its older brothers but adding five internal pins for bidirectional full duplex data exchange that we explain in the section on how a USB works.

USB 3.0 type A and type C

Micro USB type A

This Micro USB type A version is deprecated and is considered obsolete by many. All four pins are still in a horizontal line and the position of the connector is guaranteed by the shape of the port and not by the use of an internal tab.

You can find more information here: Micro-USB: What is it and what is it currently used for?

USB type B

Type B connectors are usually intended for peripherals or equipment with specific functions. Within this category we can find the following sizes:

Standard USB B

• As a general rule they are squares with two rounded corners to facilitate their correct connection. The pins are divided into two opposite pairs.

It is common to find this type of connectors for devices or peripherals that must be connected to computers such as certain printers or cash registers, among others.

Standard USB 3.0 Type B

It is an implement in data transmission speed since it adds its five pins for the full duplex. Its format is slightly thicker than the standard type B.

Mini USB Type B

Within these ports we can find two connection variants:

1. Mini USB Type B 5-pin. 8-pin Mini USB Type B

This is because most phones, cameras, or tablets require extremely small ports, but the number of contact pins required can vary based on things like charger amps (for example).

Micro USB type B

Follow the line of Micro USB type A and Mini USB type B, it appears as one more alternative to connect slim or small devices. It is the one that we have in most of our mobile devices, cameras or tablets for functions such as connecting the charger.

Micro USB 3.0 type B

Same as Micro USB type B but its format changes slightly to suit the requirements of its improved transmission speed.

USB Type-C

This is a relatively recent type of port that, to the delight of many (myself included), is not wrongly positioned. Its connectors are completely symmetrical, so the fight to put the USB in the position it should be (which is never the first attempt) is non-existent. We usually find them in peripherals such as the latest models of keyboards or smartphones .

Image: Niridya - Own work, based on: USB Type-C. Since 2009, the European Commission for the Single Market has been trying to establish a regulation to regulate the large number of connectors for mobile chargers that are on the market and unify them into a single model in a similar way to that of computer chargers. portable, although so far it has been unsuccessful. The last proposed candidate was USB Type C.

A speed comparison

Here we propose a race so that you can graphically check the difference between the different versions of USB existing to date.

As you may have observed, we have stopped to clarify aspects of the transfer rate. This is because evolution always brings with it some costs, and it is that the most common thing for the average user is not to update their hardware at the same rate as the market (which would be constantly).

Arrived here we recommend: USB 2.0 vs USB 3.0 vs USB 3.1. and as BONUS: PC connectors

All this causes that at present we have different devices or USB ports with different versions, so the data transfer that we can expect will not always be able to reach the maximum speed that is allowed. The best example of this is the bottleneck effect that is generated when we connect our pendrive 3.0 to a laptop whose port is 2.0 to pass a movie or series.

Currently the biggest problem for manufacturers is that the technology to make devices faster is already here, but what the user handles in his day to day is "obsolete".

Conclusions about USB

Let's be honest, the arrival of USB was a blessing and changed our lives in a millennium in which the digital age is already something unstoppable. With ever-increasing image qualities and resolutions, a type of universal connector was needed that lived up to the required data rate, and USB hit the field at just the right time.

Effectively we will notice the difference in speed the more recent the port version we are using, but there are factors that we must take into account over the existing versions. Having an external hard drive or USB flash drive that has 3.0 connected to a computer whose port is 2.0 will not make us get rid of the bottleneck effect when transferring data. We must take into account the version of both the transmitter and the receiver to guarantee maximum performance.