The USB port By Benjamin Perez

What is a USB?

A usb (Universal Serial Bus) is a computer port used to connect various devices to a computer. It is both an input and output depending on the device being connected. It was created to replace the many different computer ports for various devices with one universal port. There are 3 types of usb ports, click the buttons to see them all!

What's the difference between the 3 USBs?

There are only a few differences between USB type A and USB type B. USB type A ports head 'upstream' toward the computer. This makes it better for input devices like computer keyboards and mice. The USB type B moves 'downstream', connecting to individual devices, making it better for printers.

Why are there multiple types of USB ports?

There are multiple USB ports for various reasons. Each port is trying to solve the problems caused by their successor. The USB type a solved the problem where computers had a different port for every device. The USB Type B port solved the same problem. The USB type C is trying to solve the space problem caused by the other two ports. Both USB A and USB B take up a small amount of room on a computer. The USB type C is attempting to minimize the space used by the ports.

How do these ports work?

When a USB is connected to the corresponding port, it goes through a process known as enumeration. In this process, the host queries all the devices and assigns each device an address. The host then finds out what form of data transfer it wishes to preform. Devices like mice and keyboards go into the interrupt mode as it will be sending only a little bit of data. Devices like USB drives and printers choose bulk mode, meaning that it will obtain a large packet of information at one time. Streaming devices like speakers and projectors use isochronous mode, which allow for data to be streamed from the host to the device in real time without error connections. Once the device has chosen the mode it requires, it can then transfer the data inputted or outputted. Here are two videos explaining how these ports work

What is inside a USB cable?

USB cables contain four wires. A red wire that carries the power supply (-+ 5 volts), a brown wire (ground), and a pair of blue and yellow wires that are twisted together (carry the data). All these wires are shielded.

What's inside a USB drive?

This is a video that explains how the USB drive works.

How many devices can I connect to my computer at once?

You can have up to 127 devices connected to your computer, but you would require modification to your computer's ports to add more, or multiple USB port hubs. Your computer would also run slower as there is a lot of bandwidth being used.

Credits:

Created with images by janoma.cl - "USB" • espensorvik - "USB" • DeclanTM - "MacBook Ports" • cote - "Plugable 7 Port USB 3.0"

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