USB Explained

The Universal Serial Bus (USB) is a low-to-high-speed technology that provides a shared-access, highly available, robust, self-configuring, extensible, and easy-to-use serial bus that is host-computer independent and consistent across computer architectures. The advent of multimedia and the proliferation of relatively inexpensive processing power has left the venerable RS-232 a relic of times past. The USB was invented and standardized by a group of computer manufacturers and peripheral vendors in early 1995 under the auspices of an organization called the Universal Serial Bus Implementers Forum. It's goal was to define a high-speed serial bus technology to replace, or phase out, the existing RS-232 serial port technology. Today's serial bus technology must cover a full range of technology that can deliver everything from digital joysticks for high-precision game playing, to digital audio peripherals to high-resolution "live" video inupt and output devices to data networks and telephony equipment. The USB can do all of this at speeds faster than the RS-232 serial port was designed to handle. The biggest difference between a single-ended serial port (like RS-232) and a serial bus like the USB is that the traditional serial port is a point-to-point connection between a computer and a device, whereas on a "serial bus" many devices can communicate and share the connection to the computer. In the USB, up to 128 bus devices can simultaneously communicate with the host computer.