What is UART (Universal Asynchronous Receiver/Transmitter)? - Definition from WhatIs.com

Definition

UART (Universal Asynchronous Receiver/Transmitter)

Part of the Peripherals glossary:

A UART (Universal Asynchronous Receiver/Transmitter) is the microchip with programming that controls a computer's interface to its attached serial devices. Specifically, it provides the computer with the RS-232C Data Terminal Equipment ( DTE ) interface so that it can "talk" to and exchange data with modems and other serial devices. As part of this interface, the UART also:

  • Converts the bytes it receives from the computer along parallel circuits into a single serial bit stream for outbound transmission
  • On inbound transmission, converts the serial bit stream into the bytes that the computer handles
  • Adds a parity bit (if it's been selected) on outbound transmissions and checks the parity of incoming bytes (if selected) and discards the parity bit
  • Adds start and stop delineators on outbound and strips them from inbound transmissions
  • Handles interrupt s from the keyboard and mouse (which are serial devices with special port s)
  • May handle other kinds of interrupt and device management that require coordinating the computer's speed of operation with device speeds

More advanced UARTs provide some amount of buffering of data so that the computer and serial devices data streams remain coordinated. The most recent UART, the 16550, has a 16-byte buffer that can get filled before the computer's processor needs to handle the data. The original UART was the 8250. If you purchase an internal modem today, it probably includes a 16550 UART (although you should ask when you buy it). According to modem manufacturer US Robotics, external modems do not include a UART. If you have an older computer, you may want to add an internal 16550 to get the most out of your external modem.

This was last updated in February 2011
Contributor(s): Ken Conway and Michael DeHaan
Posted by: Margaret Rouse

Related Terms

Definitions

  • 3D mouse

    - A 3D mouse is a pointing and control device specialized for movement in virtual 3D (three-dimensional) environments. 3D mouse devices have used a number of different means to control 3D movement a... (WhatIs.com)

  • geo-fencing (geofencing)

    - Geo-fencing is a feature in a software program that uses the global positioning system (GPS) or radio frequency identification (RFID) to define geographical boundaries. A geofence is a virtual barr... (WhatIs.com)

  • SCSI (Small Computer System Interface)

    - Definition: Learn what the SCSI (Small Computer System Interface) is, what part it played in the history of personal computing and how it is used today. (SearchStorage.com)

Glossaries

  • Peripherals

    - Terms related to peripheral devices including definitions about keyboards or mice and words and phrases about printers, monitors, digital cameras and scanners.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question About UART (Universal Asynchronous Receiver/Transmitter)Powered by ITKnowledgeExchange.com

Get answers from your peers on your most technical challenges

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.