What is USB?

What is USB? USB (Universal Serial Bus) is a technology that you can use to connect external devices such as hard disks and flasg drives to your computer. It's easy to use and readily available.

In this article I will discuss the various technologies that make up universal serial bus and how they are used.

There are a lot of external devices out there that supports USB. The reason for this is that it's very easy to connect and use USB devices.

What is USB
What is USB Universal Serial Bus

Let's say you want to connect a external USB hard drive to your computer. You go out and buy the device. You take it out of the box and connect it to your computer using the supplied cable. It will install the driver for the device and there you go.

As simple as that!

The most known USB component must be, the USB flash drive. I know of very little people that does not have a flash drive. They are sold all over the place with different sizes and shapes. The flash drive probably contributed a lot to the development of USB.

What is USB? - Before USB
So what did people use to connect external stuff before USB? Well, it depends on what you wanted to connect. If you want to connect an external hard drive or CD/DVD drive, you had to use a controller device of some kind.

This was usually a SCSI (Small Computer System Interface) card. The adapters were expensive and the drives as well. You also needed some experience on how SCSI worked to successfully connect these devices.

Some servers even shipped with on-board SCSI controllers to make the attachment of SCSI devices easier. Mainstream PC did not have this on-board SCSI controller. It would have made it too expensive.

For printers, you usually used serial or parallel ports. These were standard on older motherboards and laptops. It was also a little easier to connect printers than SCSI devices.

Laptop and notebook users found it almost impossible to connect external devices. The industry needed a standard so that connecting external stuff is easy and cheap. This is where USB came in.

What is USB - Where did it all start?
It actually started quite a while ago. In the mid 1990's the USB standard was developed to define how external devices would connect to computers. This included the connectors, protocols, software and hardware to be used.

The first real commercial version was Universal Serial Bus version 1.1. Sure there were others before 1.1, but version 1.1 was the first successful, commercially used standard.

A multitude of devices were developed. I will list just some of the more popular devices.

Hard disks
Flash drives
Keyboard and mice
Digital cameras
Mobile phones

To name a few. There are a lot more.

Universal Serial Bus has just about replaced all other forms of external connection ports such as serial, parallel and then some.

In 2000, USB version 2.0 was released. It had faster transfer rates, supported higher voltage devices and you could also connect a lot of devices to one channel or port.

It is still used today, but version 3.0 is starting to make headway in the computer world, at the time of writing, of course.

Version 3.0 supports even faster transfers and higher voltages.

The transfer rates between the last two versions are quite significant. USB version 2.0 has a theoretical transfer rate of about 60Megabytes per second, whereas version 3.0 has a theoretical transfer rate of 640 Megabytes per seconds.

These are theoretical rates. Expect a 25-30MB/s rate for USB 2.0 on disk drives. For USB 3.0, I doubt that you will get more than around 400MB/s. These are for you normal run of the mill hard disks and flash memory sticks.

What is USB? - How do I connect a USB device
As simple as falling out of a tree. Just let go of the branch.

Seriously though, it's very simple. The developers of USB made sure that you can connect any device fast and simple. Just plug in one end of the device to your computer, and the other end to the device. The operating system should add needed software from the device if needed.

Most OS's have most of the drivers already built in, so there is no need to install drivers. Some devices might need a specialized driver. It these cases, the manufacturer of the device will ship a CD or DVD drive with their device.

Most of the times the device will also include a cable that is need to connect to the device. If not, then buy one at your local computer store.

What is USB? - What do USB connectors look like?
There are a lot of different types of connectors. If you look at your PC's USB ports, you will notice that are all the same.

The device you connect to, might have a different port. Printers, for instance, have a standard port type. There are some standard port types. Below is an image of the standard USB connectors.

What is USB - Standard connectors
standard usb connectors

If you look at the image from left to right, the ports are: Standard A receptacle, Standard A and Standard B. The standard A are found on most, if not all, computers. The standard B are mostly found on printers.

These are standard ports. On a mobile phone, for instance, these ports would be too big. On mobile and other smaller devices they have created mini or micro ports. There are too many to show you a picture here, just look at your phone. You will see what I mean.

You can also connect a lot of devices to a single USB channel or port. The standard defines that you can connect up to 127 devices together. This sounds all cool and all but the chances of this happening is remote. USB 2.0, for instance, can only handle 40MB/s, so connecting 127 devices will make it dog slow.

It's not uncommon though to have more than one device on a single port. To accomplish this you would need a Universal Serial Bus hub. This device connects to the standard A port on the computer and on the other side there are multiple USB ports. Usually also standard A ports.

Now you can easily connect more than one device to a single port. USB hubs are very common and very cheap. You can find them at your local PC store.

What is USB - Conclusions
USB has made it very easy for us to connect devices. You can now connect a multitude of devices to your computer with relative ease.

At the time of writing, Universal Serial Bus 3.0, has been introduced and I'm looking forward to work more with this technology. I will update this page as soon as I have used and played with USB 3.0 a bit more.

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