John Cletheroe's
PC And Internet Hints

PC And Internet Glossary - Including File Extensions - U

UAC

User Account Control. A highly undesirable and much hated feature of Windows Vista. To completely disable it: Control Panel > User Accounts and Family Safety > User Accounts, then click "Turn User Account Control On Or Off".

UART

"You art". Universal Asynchronous Receiver/Transmitter. The chip in a PC which handles the RS-232 COM1: and COM2: ports. Old PC's had the 8250 UART chip which is unsuitable for use with modern high speed modems. Modern PC's have the 16550 UART chip which supports higher transmission rates. I think the difference is probably the size of the buffer in the chip.

Ubuntu

A version of the Linux operating system.

UCE

Unsolicited Commercial Email. Spam.

UDDI

Universal Description, Discovery and Integration. This appears to be part of Microsoft's .NET (see that entry).

UDF

The filing system used by Adaptec/Roxio's DirectCD, which allows a CD-RW disk to be used as if it were a very slow floppy disk. UDF seems to be able to cope with all Windows 9x file and folder names and structures. It is less restrictive than Joliet and far less restrictive than ISO9660. UDF allows long file and folder names, a large number of nested folder levels and (probably) long path names. It also appears to allow all the characters that Windows 9x allows in file and folder names, although I haven't fully checked this.
In Windows, the file system driver for DVD-ROM drives.

UDP

User Datagram Protocol. A connectionless protocol which, in the same way as TCP, runs on IP networks. Unlike TCP, UDP provides few error recovery mechanisms. UDP is used primarily for broadcasting messages over a network.

UDT

User Defined Type. In Visual BASIC and possibly other programming languages, a type of variable which is defined by the programmer. The normal inherent variable types in Visual BASIC include integer numbers, floating point numbers and strings.

UHCI

Universal Host Controller Interface. A USB host controller standard. There is more information in Microsoft KnowledgeBase article 184400.

UI

User interface (of a program).

uk

The Internet top-level domain for the United Kingdom.

UMTS

The system used in 3G mobile phone networks in Europe.

UNC

Universal naming convention. I think this is the widely used system which allows a hard disk on another computer connected via a local area network to be addressed, regardless of the operating systems on each computer and also regardless of the local area network system being used.

Undernet

An IRC (Internet Relay Chat) network.

Unicode

A character code. Whereas ASCII (0-127) and ANSI (0-255) use 8 bits per character and can only properly cope with English characters, Unicode uses 16 bits per character and can cope with most of major world alphabets. In Microsoft Word, the Insert > Symbol menu option leads to a chart listing a large number of characters in various subsets; this suggests that Word and Windows 9x use Unicode. It could also partially explain why Word document files are so large, if they use two bytes per character. Microsoft KnowledgeBase article 99884 has some more information about Unicode.

Uninstallable

Capable of being uninstalled, or in other words capable of being removed from a computer.
Not capable of being installed.

A least one Microsoft KnowledgeBase article (KB810243) contains the marvellously ambiguous phrase "This file is uninstallable".

Universal Serial Bus (USB)

A method of connecting peripherals to a computer. Computers fitted with USB normally have two USB sockets.

According to some sources (and as implied by its name) USB is a bus system, allowing devices to be connected at will. According to other sources, it matters which of the two USB sockets on a PC particular devices are connected to. According to several sources connecting two PC's together via USB will definitely cause extremely serious damage to the hardware.

Most USB peripherals only have one socket, making daisy-chaining impossible.

According to some sources USB connectors can be removed and inserted with the power on. I have never risked testing this theory.

Microsoft acknowledge that USB connections with Windows 95 are extremely capricious or totally inoperative. A friend who has a Windows 95 computer and external speakers controlled via a USB connection has constant problems.

In the past Microsoft have made a USB upgrade for Windows 95 available for downloading from their web site but I believe this has now been withdrawn. It can probably be obtained from other sources. I do not know if it fixes all the problems.

On a friend's PC which has Windows 98, connecting a scanner and camera via USB causes the PC to run very slowly, Internet connections via the modem to be very slow and capricious despite a very good phone line baud rate, the software to have to make numerous attempts before successfully making the modem drop the phone line and read errors to occur on both the DVD drive and the CD-R/CD-RW drive. All these problems are all solved by removing the USB devices, except possibly the CD read errors which seem to be reduced but not eradicated. No changes whatsoever need to be made to software to solve these problems.

Since there is no locking mechanism, USB plugs can be accidentally pulled out of their sockets with very little force required, with potentially dire effects on both hardware and software if either device is switched on at the time. Since the USB plugs are a very loose fit it is also very easy to accidentally move and rotate them within their sockets, with a serious risk of shorting two PCB tracks, again with dire results.

Some modern computers and printers have USB connections instead of conventional interfaces.

A friend reported that due to their similar size and shape, a technically ignorant acquaintance of his plugged a USB cable into the Ethernet socket on a computer.

See also Firewire, which is a similar interfacing system.

Opinion: The physical design of USB connectors appears highly suspect to me, using a primitive and flimsy PCB (printed circuit board) edge connector which looks as if it will not survive many insertions and extractions before the tracks become damaged.

Unmetered Calls

Telephone calls for which the cost is not affected by the duration of the call. Unmetered calls are not the same as free calls. Because of their potentially long duration, unmetered calls may be expensive, which is a problem if you have to make several attempts to connect.

The term can also be used to describe a telephone tariff in which you pay a fixed amount in addition to your normal bill and can then make unlimited calls of a certain type. BT have recently introduced such a tariff but so far the cost is extortionate and for all but the most intensive of users the conventional "pay as you go" option is far less expensive.

Several companies have recently released plans to introduce unmetered calls for Internet access in the UK. These include Alta Vista, LineOne and NTL. In each case these are not free services - there are one-off, monthly or annual charges. In some cases additional equipment has to be purchased. However, these offers may well work out less expensive than the standard BT tariff for people who make heavy use of the Internet.

Any totally free or very inexpensive ISP service is likely to suffer from serious technical problems due to over-subscription. It may also feature highly intrusive advertising.

Long term, the opening up to competition of the local loop (the telephone cable from each property to the exchange) and the introduction of ADSL may well have a more drastic effect on Internet access charges in the UK.

Up

Operative. A computer or a network which is "up" is operative. "Up and running" means exactly the same thing - I don't see how something can be up but not running, or vice versa.

UPD:

Microsoft KnowledgeBase article title prefix for articles relating to updates (patches).

Update

Microsoft KnowledgeBase article 824684 includes the following definition of this term as used by Microsoft: "An update is a broadly released fix for a specific problem. An update addresses a non-critical, non-security-related bug."

Update Rollup

Microsoft KnowledgeBase article 824684 includes the following definition of this term as used by Microsoft: "An update rollup is a tested, cumulative set of hotfixes, security updates, critical updates, and updates that are packaged together for easy deployment. A rollup generally targets a specific area, such as security or a component of a product."

Upgrade

Microsoft KnowledgeBase article 824684 includes the following definition of this term as used by Microsoft: "An upgrade is a software package that replaces an installed version of a product with a newer version of the same product. The upgrade process typically leaves existing customer data and preferences intact while replacing the existing software with the newer version."

Upload

To copy one or more files from your PC to another computer via the Internet. The most common example of uploading is copying web site files (HTM, GIF, JPG files, etc) that you have created on your PC to your personal web site area on your ISP's server in order to make them available on the Internet. Uploading normally involves the use of an FTP program, a well known example being WS_FTP.

UPNP

Universal Plug And Play. Plug And Play for network equipment. I don't know if any UPNP device are actually on sale or whether the concept is just vapourware.

Upper Case

Capital letters.

URL

Uniform Resource Locator. In casual terms, a web site address. More precisely, the address of any server, folder, file or other resource on the Internet.
A full URL of a web page file consists of the following parts, in this order:
- The http:// device name prefix, which officially means Hypertext Transfer Protocol but which can be thought of as meaning the World Wide Web. Optional in most modern web browsers, which automatically add it if the user omits it. Should not be included for a file on your own computer.
- The domain name of the server. Defaults to the computer on which you are working. Domain names consist of a set of names at each level, separated by full stops (periods), the top level being at the righthand end and the lowest level being at the lefthand end. For example, "www.microsoft.com" is the "www" server within the "microsoft" domain within the ".com" top-level domain. Many modern web browsers have an option to automatically add the "www." section at the start of the domain name if the user omits it and it is required. Some browsers will also automatically add ".com" on the end of the domain name if it is omitted and required.
- A path - a list of nested folder/directory names, separated by single forward slashes, for example /products/widgits/pricelist/ (meaning the pricelist folder within the widgits folder within the products folder). In a web browser's OPEN dialog box or URL line the path defaults to the "root" directory of the area of the server which is available for public access via the web. In a hypertext link in a web page the path defaults to the same server and folder as the current page's web page file is in.
- A filename and extension of a web page file (separated by a full stop). This defaults to index.htm or index.html (there are several other possibilities, I believe, and if any of these files exist in the relevant folder then they will be loaded). Web page file extensions include HTM, CGI and ASP (see those entries).
- A hash sign (#) followed by a section name within the web page, defined by means of a <A NAME = "...">...</A> tag. If this is section of the URL is omitted, as is often the case, then a web browser will display the top of the web page.
- File extension. Internet shortcut.
Controversy: Should you say "an URL" (since URL starts with a vowel) or "a URL" (since you spell out the acronym and say the U as "you" which starts with a consonant)? I strongly favour the latter option.
File extension. URL files can contain instructions which could perform undesirable operations on a computer.

US-CERT

See CERT.

USB

Universal Serial Bus - see that entry.

UseNet

See News.

Uuencode

See BinHex and MIME.

UUID

Universal Unique Identifier. According to one source, each local area network card has a built-in permanent UUID which is extremely likely (but not quite guaranteed) to be unique. This is different to an IP address, which is assigned by software. According to the same source, a UUID is the same as a GUID (Globally Unique Identifier). However, a different source suggests that a GUID is a unique Microsoft product code, and therefore possibly associated with the dreaded Microsoft Product Activation system.

UVW Mapping

In 3D graphics programs, the standard method of specifying which parts of a two dimensional bitmap texture file should be applied to which parts of a three dimensional mesh object.

UWB

Ultra Wide Band. A new wireless system which may offer very fast transmission rates.

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