U
* UMA: Unified Memory Architecture
* Unbuffered Memory
* Unipolar Transistors
* Uniprocessor
* UPnP: Universal Plug and Play
* UPS: Uninterruptible Power Supply
* USB 2.0: Hi-Speed USB
* USB Flash Drive
* USB OTG: USB On-The-Go
* USB: Universal Serial Bus
* UTP: Unshielded Twisted Pair
UMA: Unified Memory Architecture
Unified Memory Architecture (UMA) is a computer architecture in which graphics chips are built into the motherboard and part of the computer's main memory is used for video memory.
Unbuffered memory
Unbuffered memory, also known as unregistered memory, is memory where the memory controller module drives the memory directly, instead of using a store-and-forward system like registered memory. The use of unbuffered memory is reasonable for gaming systems. It is not recommended for server-class systems.
Unipolar transistors
Unipolar transistors, also called Field-effect transistors (FET), use only one of the two types of carrier (either electrons or holes, depending on the subtype of the FET). In FETs the main current appears in a narrow conducting channel with an insulating depletion zone at the side. The width of this insulating zone can be altered by varying the voltage applied to the gate terminal, enlarging or constricting the conducting channel and thereby controlling the main current.
Uniprocessor
A uniprocessor system refers to a system with a single processor. As more and more computers employ multiprocessing architectures, such as SMP and MPP, the term is used to refer to a system that still has only one CPU. Although most desktop computers are uniprocessor systems, it is expected that dual processor systems will become commonplace on the desktop in the coming years.
UPnP: Universal Plug and Play
Universal Plug and Play (UPnP) is an architecture for pervasive peer-to-peer network connectivity of intelligent appliances, wireless devices, and PCs of all form factors. The scope of UPnP is large enough to encompass many existing, as well as new and exciting scenarios including home automation, printing and imaging, audio/video entertainment, kitchen appliances, automobile networks, and proximity networks in public venues. UPnP is a distributed, open networking architecture that leverages TCP/IP and the Web technologies to enable seamless proximity networking in addition to control data transfer among networked devices. Under UPnP, there are no device drivers; common protocols are used instead. UPnP networking is media independent. UPnP devices can be implemented using any programming language, and on any operating system.
UPS: Uninterruptible Power Supply
Uninterruptible Power Supply (UPS) is a device that provides power backup when the normal electricity fails or drops to an unacceptable voltage level. UPS systems can provide power from a a few minutes to several hours. In mission critical data centers, UPS systems are used until electrical generators take over. UPS systems can be set up to alert file servers to shut down in an orderly manner when an outage has occurred, and the batteries are running out.
USB 2.0: Hi-Speed USB
USB 2.0, an enhancement of USB 1.1, is a high speed external bus that supports data rates up to 480Mbps. USB 2.0 is fully compatible with USB 1.1 and uses the same cables and connectors. Not all USB 2.0 devices are Hi-Speed. A USB device should specify the speed it will use by correct labeling on the box it came in or sometimes on the device itself. The USB-IF certifies devices and provides licenses to use special marketing logos for either "Basic-Speed" (low and full) or High-Speed after passing a compliancy test and paying a licensing fee.
USB flash drive
A USB flash drive, also known as "flash memory", "pen drives", "thumb drives", "flash drives", "USB keys", is flash memory integrated with a USB 1.1 or 2.0 interface used as a small, lightweight, removable data storage device that plugs into a computer USB port and functions as a portable hard drive. Flash drives are active only when powered by a USB computer connection, and require no other external power source or battery power source.
USB OTG: USB On-The-Go
USB On-The-Go (USB OTG) is a supplement to the USB 2.0 specification. USB uses Client/Server Architecture. USB OTG products can communicate with each other without the need to be connected to a PC. So one USB device acts as a USB host and the other acts as USB peripheral. Only the USB host contains the device driver and the necessary controls to transfer the data. For example, a digital camera can connect to a PDA, or a mobile phone can connect to a printer or a scanner, as long as all the devices are USB OTG-compatible. USB OTG grew from the increasing need for portable devices to be able to communicate with each other as the culture of technology moves away from a PC-centric world.
USB: Universal Serial Bus
Universal Serial Bus (USB) is an external bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging. A USB system has an asymmetric design, consisting of a host controller and multiple devices connected in a tree-like fashion using special hub devices. There is a limit of 5 levels of branching hubs per controller.
UTP: Unshielded twisted pair
Unshielded twisted pair (UTP) is a popular type of cable that consists of two unshielded wires twisted around each other. It is a variant of twisted pair cabling. The cable which connects most computers to their network will be a UTP cable. UTP cabling is used extensively for local-area networks (LANs) and telephone connections.