Visual Display Unit
Display Screen Equipment
(VDU, or "video terminal", "video display terminal", VDT, "display terminal") A device incorporating a cathode ray tube (CRT) display, a keyboard and a serial port. A VDU usually also includes its own display electronics which store the received data and convert it into electrical waveforms to drive the CRT.
Early VDUs could only display characters in a single preset font, and these were confined to being layed out in a rectangular grid, reproducing the functionality of the paper-based teletypes they were designed to replace.
Later models added graphics facilities but were still driven via serial communications, typically with several VDUs attached to a single multi-user computer. This contrasts with the much faster single bitmap displays integrated into most modern single-user personal computers and workstations.