XT

The original version of the first IBM PC, developed by IBM, that used an 8088 processor and included a hard disk .

Xmodem

A communications protocol that allows you to transfer files between your computer and a network with error correction.

XT keyboard

A type of keyboard used by the IBM PC which had ten function keys running in two columns along the left-hand side of the keyboard. The current standard is called the AT or Windows 95 keyboard. These include 12 function keys and, in the case of a Windows 95 keyboard, a special button that's equivalent to pressing the Start button on screen.