USB

USB:
Universal serial bus.
Used to connect other devices.
It can connect up to 127 devices with one cable.
Replaced Parallel and serial ports.

Why Parallel and Serial ports are replaced by USB?
Mouse is dedicated to transmitting serial data.
Printer use parallel data cable.

How Serial port works?
Transfers data one by one.

How Parallel port works?
8 bits at a time.

History of USB:
Development started in the year 1994 by Ajay bhatt.

Types of data transfer in USB:
Control transfer.
Isochronous transfer.
Interrupt transfer.
Bulk transfer.

Control transfer:
Device handles one request at a time.
Host sends a request to a device.
Data transfer takes place in pipes.

Isochronous transfer:
Unidirectional.
Doesn't have to be accurate.

Interrupt:
Used for small, infrequent transfers.

Bulk transfer:
Sending data from devices like scanners.

Difference between USB 0.8, 1, 1.1, 2, 3.0, 3.1?

Features	0.8	1	1.1	2	3	3.1
Speed	1.5Mb/s	12Mb/s	12Mb/s	480Mb/s	5Gb/s	10Gb/s
Data transfer	One side	One side	One side	One side	Both side	Both side
Power	5v, 1.5A	5v, 1.5A	5v, 1.5A	5v, 1.8A	5v, 1.8A	20v, 1.8A
Encoding	Unicode	Unicode	Unicode	Unicode	8b/10b	8b/10b
Backward compatibility	Yes	Yes	Yes	Yes	Yes	Yes
Max cable	3meter	3meter	3meter	5meter	3meter	3meter
Release	1994	1996	1998	2000	2008	2013

USB storage:
Implements connection to a storage.
By connecting data transfer takes place.

Connector properties:
Receptacles and plugs.
Usability and orientation.
Durability.
Compatibility.

Receptacles and plugs:
To contain something is called Receptacle.
Connector attached to a cable.

Usability and orientation:
Provides easy view for connecting.

Durability:
Ability to last with pressure.

Compatibility:
Capable of being packed.

Connector Types:
Type A.
Type B.
Type C.
Micro A.
Micro B.
Mini B.
Type 3 A.
Type 3B.
Type 3 micro B.

Type A:
Flat, rectangular.
Easy to connect and deconnect.
Downstream connection.