Τεχνικός Υπολογιστών CompTIA A+

Ειδικά | Α | Β | Γ | Δ | Ε | Ζ | Η | Θ | Ι | Κ | Λ | Μ | Ν | Ξ | Ο | Π | Ρ | Σ | Τ | Υ | Φ | Χ | Ψ | Ω | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | ΟΛΑ

---

UAC (User Account Control) A Windows dialog box that appears and asks permission to do something that might be harmful or change the operating system environment. Some changes require an administrator password to continue.

Ubuntu Software Center A software manager to access Ubuntu’s repositories of open source software. It can install new applications and uninstall existing ones, many of which are available for free.

UDF (Universal Disk Format) A file system used for DVDs so data can be read and acted upon through the operating system, as for other devices, such as a flash drive.

UDF (user-defined function) Something built into a program that allows a specific function to be provided by the person using the program.

UDP (User Datagram Protocol) A Layer 4 connectionless standard that applications use to communicate with a remote device.

UEFI (Unified Extensible Firmware Interface) The replacement for the traditional BIOS that has a boot manager instead of the BIOS controlling the boot process. The UEFI environment allows for a graphic interface, the use of a mouse, antivirus software to be used before the operating system loads, and Internet access.

UL 1449 VPR A voltage protection rating standard developed by Underwriters Laboratories to measure the maximum amount of voltage a surge protector allows through to attached devices.

unable to decrypt email In this situation, use S/MIME, use a web browser add-on, or obtain the security certificate.

unable to install printer In this situation, check cabling and power; follow the manufacturer’s instructions; delete the print driver and try installation again; download a different print driver and try installation again; research the error on the manufacturer’s website; and document.

unattended installation A method of installing Windows in which the remote computer does not have to be touched. Use Microsoft Deployment Toolkit with Configuration Manager or another imaging product.

unavailable resources A symptom of a network problem in which the network device cannot access the Internet, a network printer, a network share, a particular server, email, and/or other resources.

unbuffered memory Memory that does not delay all data transfers by one clock tick to ensure accuracy as registered memory does. Used in low- to medium-powered computers.

UNC (universal naming convention) Used at the command prompt to obtain network shares.

undervoltage A condition that occurs when AC power drops below 100 volts, which may cause the computer’s power supply to draw too much current and overheat.

unexpected shutdowns A symptom of an issue with the processor, motherboard, or power supply.

unique identifier An item that must be removed during the Windows image creation process before deploying an image to computers. Unique identifiers include the computer name, security identifier (SID), network domain.

Unity The graphical user interface in Ubuntu. It has some similarities to the user interface of macOS, but it is drastically different from Windows.

unlock account In Active Directory, locate the user account and right-click on it > select Reset Password > use the Unlock the User’s Account checkbox.

unmanaged switch A type of switch that cannot be remotely accessed and is commonly found in home and small business wired networks.

unshielded twisted pair See UTP and see also twisted pair cable.

untrusted source A security measure that is built in to some browsers and security software that indicates whether a website or downloaded file is a trusted or untrusted software source.

update boot order One thing that can cause a Windows computer to not boot is the boot order in the BIOS/UEFI settings.

update network settings A device might need the network settings updated in order to get onto the wired or wireless network. This could involve using the ipconfig /release and ipconfig /renew commands or changing the IP address to a manually assigned one.

updatedb A Linux command that updates the file database.

upgrade To install a newer or more powerful operating system where one already exists. An upgrade can also involve installing newer hardware.

UPnP (universal plug and play) An alternative to port forwarding that allows peer-to-peer (P2P) gaming applications to function without further configuration.

UPS (uninterruptible power supply) A device that provides power for a limited time to a computer or device during a power outage.

upstream Describes information that is sent to the Internet, such as transmitting email or uploading a file to a server.

upward compatibility A technique used by a software manufacturer when a product is designed in such a way that it can accept input intended for a future version. Another name for forward compatibility.

URL (uniform resource locator) A method of accessing Internet resources.

usable host numbers The number of host bits (and associated IP addresses) that can be used by network devices residing in a subnetwork.

usable subnets The number of subnetworks that can be used when an IP network number is subdivided to allow more efficient use of IP addresses.

USB (universal serial bus) A bus that allows 127 devices to be connected to a single computer port.

USB 2.0 A standardized port that supported speeds up to 480 Mb/s, a maximum of 0.5 amps, 5 VDC, as well as Type A and Type B connectors.

USB 3.0 A standardized port that supports speeds up to 5 Gb/s, a maximum of .9 amps, and 5 VDC.

USB 3.1 A standardized port that supports speeds up to 10 Gb/s and supports the Type C connector.

USB A-to-USB B converter Connector cable with a USB A plug and a USB B plug.

USB expansion card A metal plate that has one or more USB ports and a cable that connects to the motherboard. The metal plate fits in a slot that a normal card in an expansion slot would take.

USB flash drive Sometimes called a flash drive or a memory stick, a drive that allows storage via a USB port.

USB lock A security device that prevents USB storage devices from being inserted into a USB port.

USB port A port on a motherboard or on an adapter that allows the connection of up to 127 devices.

USB to Bluetooth An adapter that connects Bluetooth to a laptop or mobile device that has a USB port.

USB to RJ-45 dongle An adapter that connects Ethernet to a laptop or mobile device that has a USB port.

USB to WiFi dongle An adapter that connects WiFi to a laptop or mobile device that has a USB port.

USB Type-A An upstream male connector on a USB cable that connects to an upstream Type-A port on a host computer or other hub.

USB Type-B A downstream male connector on a USB cable that connects to a Type-B connector on the downstream device.

USB Type-C A reversible plug connector for USB devices and hosts and that will eventually replace USB Type-A/Type-B plugs.

USB-C See USB Type-C.

USB-PD A USB power delivery standard that allows up to 20 V at 5 A for 100 watts of power. The standard has five levels of power: 10 W, 18 W, 36 W, 60 W, and 100 W.

USB-to-Ethernet converter A connector cable with a USB plug and an Ethernet end.

---