Appendix Glossary U

In the left margin you will find links to the glossary categorised alphabetically. Some of the pages are quite long and may take a few moments to load if you use a modem. This glossary is always being updated.

Glossary - U

UDMA - Ultra direct memory access. A hard drive specification that provides up to 33 MB/sec transfer rates from inexpensive mass storage devices connected to the EIDE bus. UDMA requires a supported motherboard (or UDMA controller card add-on), a UDMA-compatible drive, and a supported operating system (e.g., Windows 98). An updated version of the specification, known as UDMA/66, available since mid-1999, provides performance comparable to much more expensive Ultra Wide SCSI 2 drives, with up to 66 MB/sec transfer rates. The BX chipset does not support UDMA/66, although several motherboards from Abit (BE-6, BP-6, etc.) and a few products from other motherboard manufacturers have added support to this chipset themselves (and, with it, introduced some compatibility problems, too). A new generation of motherboards based on the i820, i840, VIA Pro 133 or later chipsets (or add-on UDMA/66 controller cards) is the best way to take full advantage of UDMA/66 devices. Most recently, UDMA has been updated yet again, to a new spec known as UDMA/100. As the name implies, it supports data transfer rates up to 100 MB/sec.

UI - (User Interface) The part of an application the user experiences as opposed to the internal functioning of the program.

Ultra ATA/100 - Ultra ATA/100 or Ultra DMA/100 is an extension of the current Ultra ATA/66 interface. This new high-speed interface has the capability of 100 Mbytes/sec transfer rate and maximised disk performance under the current PCI local bus environment.

Undo - A command included in many word processing and graphics software applications that allows a user to eliminate or reverse the last action. For example, say you've just applied a moustache to the Mona Lisa with your new paint program. You then decide you like the painting better the way it was originally. With a click of the undo button or command, the moustache is gone. In many Windows compatible programs, pressing the Ctrl and Z keys together will accomplish the same thing as the undo feature.

Undocumented - Features included in a program that were not described in the users manual. Sometimes undocumented items are left out unintentionally. Sometimes undocumented features were present to facilitate the writing of the program by the designers and programmers and thought to be unimportant to the end-user. Other times, such features are present as part of a test in determining whether they will be included in future versions of the program.

Unbuffered Memory - Memory that does not contain buffers or registers located on the module. Instead, these devices are located on the motherboard.

Unformatted Capacity - The total number of usable bytes on a disk, including the space that will be required later to record location, boundary definitions, and timing information.

UNIX - "Universal Interactive Executive" UNIX is a computer operating system that was introduced by Bell Laboratories back in the dark ages of computing, but is still in widespread use today. It's not for the faint of heart, though. Despite its undeniable values in high-end computing, it is far from intuitive. Fortunately for the rest of us, the UNIX operating system is typically employed only by hard-core computer users who know what they're getting into. It is known for it's stability, it's speed, it's free software packages, and many program development libraries.

Unpack - To convert a compressed file to its original form.

Upload - The act of copying a file to a network or large data repository (such as a web page or FTP site) from an individual computer's disk drive. Simply stated, uploading is the process of "giving" a file to a server. Uploading is the transmission of a file from your personal computer to another computer.

URL - "Uniform Resource Locator" URLs are the textual or numerical addresses of specific pieces of information on the Internet. In order to access a web page, for instance, one must know the URL that corresponds with that particular page. Entering a URL to view a website is very much like dialling a telephone number to reach a company or individual. URLs are usually found as links on web pages, but are turning up more often in posts on USENET and in e-mail messages. Upper and lower case are often important in URLs. The URL is usually made up of four parts which specifies the type of the resource (e.g. gopher, http, ftp), the hostname, followed by the path at the host site and the name of the document or other resource. Example: http://www.scotsmist.co.uk/index.html

USB - Universal Serial Bus. Typically located on the back of the computer near the expansion bay area, USB ports provide an easy way to connect USB-compatible peripherals such as scanners, cameras, joysticks, mice and keyboards (etc.). To connect more than two USB devices, you will have to add an item with more ports known as a USB hub.

USB 2.0 - A faster variant of USB, providing transfer speeds up to 480 Mbps. Announced in April 2000.

USENET - The "user's network." A large network connected to the Internet. It contains Newsgroups or discussion areas on almost any topic available. Messages are posted publicly for all to see.

User - The person who operates a computer or runs a program. The computer then would be the user.

User Friendly - Any software or hardware that allows for easy operation by a user. Operating systems using graphical user interface features such as menus, buttons, onscreen clickable items, and a mouse all contribute to the degree of userfriendliness of home computers.

User Interface - The means by which an individual communicates with a computer through a software application. The common methods for such communication are, commands, menus, and icons.

UTP - Unshielded twisted pair. Also referred to as 10BASE-T or 100BASE-T network cable.

Uunecode - A UNIX utility program used to convert binary files into ASCII for the purpose of posting to a newsgroup or sending email attachments.