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U
UDP |
Ultra DMA
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UNC | Unix | Upload
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URL |
USB
UDP
Stands for "User Datagram
Protocol." It is part of the TCP/IP suite of protocols used for data
transferring. UDP is a known as a ?stateless? protocol, meaning it doesn't
acknowledge that the packets being sent have been received. For this reason, the
UDP protocol is typically used for streaming media. Though you might see skips
in video or hear some fuzz in audio clips, it's better than having to wait for
the delayed packets, causing the clip to completely stop.
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Ultra
DMA
This technology for transferring data between a computer's hard disk and memory
was developed by Quantum and Intel. The maximum burst rate of an Ultra DMA hard
drive is 33.3 MBps. The original DMA (Direct Memory Access) protocol could only
transfer data at half that speed.
Thanks to Ultra DMA, programs can open faster and run more smoothly. This is
because Utlra DMA can send more data to the memory in less time than the
original DMA. Ultra DMA also has a built-in utility called Cyclical Redundancy
Checking (CRC) that helps protect data integrity. So if you want a nice, fast
hard drive, look for one that supports Ultra DMA.
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UML
Stands for "Unified Modeling Language." This is a programming language that is
used for object-oriented software development. To organize program code more
efficiently, programmers often create "objects" that are sets of structured data
within programs. UML, which has been standardized by the Object Management Group
(OMG), was designed for this purpose. The language has gained enough support
that it has become a standard language for visualizing and constructing software
programs.
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UNC
Stands for "Universal Naming Convention," not just the home of the North
Carolina Tar Heels. This is a filename format that is used to specify the
location of files, folders, and resources on a local-area network (LAN). The UNC
address of a file may look something like this:
\\server-name\directory\filename
UNC can also be used to identify peripheral devices shared on the network,
including scanners and printers. It provides each shared resource with a unique
address. This allows operating systems that support UNC (such as Windows) to
access specific resources quickly and efficiently.
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Unix
Also known as UNIX, though the letters don't stand for anything. The Unix
operating system was first created in Bell Labs way back in the 1960s. It became
popular in the 1970s for high-level computing, but not on the consumer level.
Since a lot of Internet services were originally hosted on Unix machines, the
platform gained tremendous popularity in the 1990s. It still leads the industry
as the most common operating system for Web servers. Yet Unix remains somewhat
of an ambiguous operating system, as there are many different versions of it.
Some examples include Ultrix, Xenix, Linux, and GNU, which, making things even
more confusing, all run on a number of different hardware platforms. Most people
don't ever need to use Unix, but computer geeks seem to have the need to use it
as much as possible.
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Upload
While downloading is receiving a file from another computer, uploading is the
exact opposite. It is sending a file from your computer to another system.
Pretty straight forward. It is possible to upload and download at the same time,
but it may cause slower transfer speeds, especially if you have a low bandwidth
connection. Because most files are located on Internet servers, people generally
do a lot more downloading than uploading.
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URL
Stands for "Uniform Resource Locator." It is the address of a specific Web site
or file on the Internet. A URL cannot have spaces or certain other characters
and uses forward slashes to denote different directories. Some examples of URLs
are http://www.sharpened.net/glossary/index.html, http://www.wheaton.edu/, and
ftp://info.apple.com/. As you can see, not all URLs begin with "http". The first
part of a URL indicates what kind of resource it is addressing. Here is a list
of the different resource prefixes:
http - a hypertext directory or document (such as a web page)
ftp - a directory of files or an actual file available to download
gopher - a gopher document or menu
telnet - a Unix-based computer system that you can log into
news - a newsgroup
WAIS - a database or document on a Wide Area Information Search database
file - a file located on your hard drive or some other local drive
The second part of a URL (after the "://") contains the address of the computer
being located as well as the path to the file. For example, in "http://www.cnet.com/Content/Reports/index.html,"
"www.cnet.com" is the address or domain name of the host computer and
"/Content/Reports/index.html" is the path to the file. When a address ends with
a slash and not something like ".html," the server usually defaults to a file in
the current directory named "index.html". So, if you type in "http://www.ptv.com.pk/"
and "http://www.ptv.com.pk/index.asp," you should get the same page.
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USB
Stands for "Universal Serial Bus." It is today's most commonly used type of
computer port. USB can be used to connect a mouse, keyboard, game controllers,
printers, scanners, digital cameras, and removable media drives, just to name a
few. With the help of a few USB hubs, you can connect up to 127 peripherals to a
single USB port and use them all at once (though that would require a lot of
dexterity). USB is also faster than older ports, such as serial and parallel
ports. The USB 1.1 specification supports data transfer rates of up to 12Mb/sec
and USB 2.0 has a maximum transfer rate of 480 Mbps. Though USB was introduced
in 1997, the technology didn't really take off until the introduction of the
Apple iMac (in late 1998) which used USB ports exclusively. It is somewhat
funny, considering USB was created and designed by Intel, Compaq, Digital, and
IBM. Now USB has become a widely-used cross-platform interface for both Macs and
PCs.
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