Letter U
UAC                User Account Control. Introduced in Windows Vista to secure
                   against unwanted installs esp. malware when using internet.
                   THer are two settings in Vista, but extended to 4 in Windows 7.
                   
UAE                Umbiqious Amiga Emulator. Program to emulate a Commodore Amiga
                   on PCs, Macs and Unix machines.

Ubuntu             A popular variant of the Debian Linux operating system. Variants include
                   Server, Desktop, KUbuntu (KDE), Lubuntu (LXQt), Ubuntu Budgie, 
                   Ubuntu Kylin, Ubuntu MATE (Gnome), Ubuntu Studio, Xubuntu (Xfce).

UDMA               Ultra Direct Memory Access disks. Type of very fast IDE disks.


UDP                User Datagram Protocol. Used by various IP protcols such as 
                   DNS, WINS, Authentication and Security protcols.

UEFI               Unified Extensible Firmware Interface. A ROM chip that contains
                   firmware to allow hardware to boot Operating System. Supports large disks,
                   CPU independant, flexible pre-OS environment, modular design.
									 
UHCI               Universal Host Controller Interface for USB ports (see OHCI).

UHD                Ultra High Definition. Very high resolution used on television of 2160p or
                   3840 x 2160 pixels (8 million pixels). Also, known as 4K.

UML                Unified Modelling Language. Language used to design programs.

Universal          Universal binary app for macOS applications like PPC/Intel or Intel/ARM M1.
                   See Apple developer site.

UNIX               Trademark name for early AT&T operating system. Also, applies to Solaris,
                   BSD and some others but not Linux.

Upload             Process where files are copied from your local computer to a 
                   remote computer using software such as FTP. (See Download).


UPnP               Universal Plug and Play for auto-configuration of devices over a network.


UPS                Uninterruptable Power Supply. A battery backed up power supply 
                   which can protect computer equipment from spikes, surges and 
                   power loss for short periods of time.

URL                Uniform Resource Locator. The address of a web site such as
                   http://www.yahoo.com/.

USB                Universal Serial Bus. New standard which replaces the serial,
                   parallel, game and floppy ports with a faster port which can do
                   all of the above and allow devices to be chained together and
                   be 'hot-swappable'.
							                    
Utility            Name given to small programs that do a small function such as look
                   at a text file, view a picture or animation or some other small
                   function. They are stored in the Utilities drawer.


UTP                Unshielded Twisted Pair. Network cable that uses pairs of twisted
                   cable for high speed data transfer.



UUID               Universally unique identifier. A 128 bit number identifier for objects
                   in a computer system. See also GUID.

UUX                Uuencoding. Encoding method for sending binary files as ASCII
                   files especially via E-Mail. Replaced by MIME.
                   
UWP                Universal Windows Platform for apps that run on Windows 10.
                   Replaces WinRT apps on Windows 8.