Prepared in conjunction with the panel Getting Systems Support: Speak Their Language or Do-It-Yourself, Monday, June 9th, 1997, Seattle
This brief glossary has been culled from a variety of sources, including Howard Besser and Jennifer Trant's Introduction to Imaging (1995), Printing Impressions (March 1997), a large contribution from Carolyn Edds, and Fortune Technology Buyer's Guide (Winter 1997).
algorithm:
A rule governing computer processes, often mathematical.
analog:
A continuously varying indicator representing changing values, as
in an analog watch, which uses movable hour, minute and second
hands.
application program/application software:
A program or software that performs a specific task, such as word
processing or database management.
architecture:
The configuration of the hardware and software in a computer
system.
ASCII:
American Standard Code for Information Interchange: A standard
that defines which values are used for letters, numbers, and sym
bls by using a 7-bit code and an 8th check bit.
backbone:
A network cabling segment that interconnects a group of network
segments or systems. The backbone is often dedicated to server
traffic or kept between wiring closets (housing MSAUs,
concentrators, or hubs) so the systems can operate faster or over
longer distances.
bandwidth:
The transmission capacity of a communications channel, usually
expressed in bits or bytes per second (the former is also called
baud rate).
bit:
The smallest unit of computerized information. In the computer's
binary language this is the simple on and off code.
bit-mapped image:
An image created from a series of bits and bytes that form
pixels. Each pixel can vary in color or gray-scale value. Also
known as a raster image.
bridge:
A device that links two networks that use the same protocol. This
may be used to extend the network or to connect two different
network transport technologies (such as EtherNet and Token Ring).
browser:
Software that makes it possible for a networked computer to find
and retrieve information over the Internet. Web browsers let you
display the graphical information that makes up the World Wide
Web.
buffer:
Temporary storage space within a computer system.
bus:
The pathway on a chip or circuit board that sends and receives
data. The bus on a computer's main circuit board, often called
the motherboard, has slots for expansion cards.
byte:
Eight bits.
cache:
The portion of random access memory (RAM) set aside as a
temporary storage or buffer to speed up communications between
the CPU and a hard disk or slower RAM.
client/server:
A systems architecture design that divides functions (which might
be part of a single application) between two or more computers.
The client is the machine that requests information; the server
is the machine that supplies it.
compression/decompression:
Compression is the process of squeezing more data into a smaller
storage space. Decompression is the retrieval of compressed data
and its reassembly to resemble its original form (before
compression).
CPU:
Central Processing Unit. The computer's internal storage,
processing, and control circuitry.
DAT and DLT:
Digital audio tapes are cassette tapes that store data in digital
form for data management purposes. Ideal uses for this
inexpensive medium are long-term archival storage. Digital linear
tape is effective for long-term storage applications and is best
suited for use by high-volume printers, as opposed to desktop
publishers.
database:
Any collection of data can be referred to as a database. In the
computer field, this term has come to mean a file or set of files
that stores data in a retrievable format for later recovery or
record-keeping.
digitizing:
To convert an image into binary code. Visual images are digitized
by scanning them and assigning a binary code to the resulting
vector graphic or bitmapped image data.
domain name:
The Domain Name System, better known as DNS, translates computer
names into their associated IP addresses (the numerical address
internally used for sending messages), so that you don't need to
know the IP address of a computer.
download:
The transfer of information from one computer to another.
Frequently used to describe file transfer from a network file
server to a personal computer.
email:
An electronic document-exchange tool used for interpersonal
communications that can send and receive text, files, and audio
items. A central application is responsible for storing the
information, forwarding it to the proper recipient, and possibly
tracking that activity. A user interface application enables the
user to create, retrieve, and send messages.
encryption:
A method of coding that makes files unreadable to those that
don't have the decryption code.
EPS:
Encapsulated PostScript. An image storage format that extends the
PostScript page description language to include images.
ethernet:
A network protocol that transfers data at 10 Mbits/s across a
linear bus topology.
fiber optic:
A technology that uses laser light pulses, sent over thin glass
fibers, to deliver at high speeds (up to several gigabits per
second).
file server:
A computer running a special operating system that allows
authenticated PCs to access files (rather than disk sectors) on a
shared portion of its hard disk.
firewall:
Security on the Internet is clearly a vital topic of interest to
many people. There are many types of security that can be
implemented, but one of the most effective is a hardware and
software combination known as afirewall. Basically, a
firewall protects a network from many well-known security attacks
coming in from the Internet. A firewall acts as a gateway through
which all Internet traffic going to a network moves. On that
gateway is software that checks all the incoming and outgoing
messages looking for anything that might be dangerous. Without
assuming that a message is or is not dangerous, the firewall
routes the messages to a safe area which is easy to monitor. Most
firewall software makes using Internet services a bit more
difficult for people on the network behind the firewall. However,
if the firewall is set up properly, those people's data is much
safer than if the firewall didn't exist. Thus, the tradeoff of
security for convenience is often considered a good one.
format:
Formatting: One of the basic tasks handled by the computer's
operating system that establishes a pattern for the display,
storage, or printing of data. The process of adjusting the
appearance of a document.
FTP:
File Transfer Protocol is a service for transferring files
between computers. It supports two types of data: binary (which
allows any kind of file to be transferred) and text (which
restricts transfers to files that contain text only). FTP also
allows for unattended file transfer, where you can schedule a
file exchange to occur at a particular time (say, late at night
when communication costs are lower) and the job will be done
without operator interaction.
gateway:
A device that translates data between two systems that are
incompatible or that use different protocols.
groupware:
Programs that enable many people on a computer network to work
simultaneously on the same file, while viewing the changes made
by others as they occur.
hardware:
The actual machine and its physical components that make up a
computer.
header:
Technical information packaged with an image or text file, which
may be of use in displaying the image or text.
HTML:
Hypertext Markup Language. An encoding format for identifying and
linking electronic documents used to deliver information on the
World Wide Web.
HTTP:
Hypertext Transport Protocol. A standard used for sharing
information on the Internet. It is the basis for the World Wide
Web.
hub:
A cabling center in a star topology that either amplifies a
signal and transmits it (active hub) or simply passes the signal
along (passive hub). This term is properly used to describe such
devices in ARCnet networks, but it has become generic, describing
all devices used in a back-to-center (home run) cabling
configuration. (Examples: 10BaseT EtherNet concentrators and
Token Ring MSAUs, which technically are not hubs.)
IP:
Internet Protocols. The standards that enable computer users to
exchange data through the Internet.
ISDN:
Integrated Services Digital Network. Offers multiple voice and
data channels over the same connection. up to 24 channels running
at 64 kilobit/sec are available for a maximum of 1.544 Mbit/s on
a single ISDN connection. The biggest problem with ISDN is that
it's a little long in the tooth now. When the standard was first
proposed it was a fine fit with existing technologies, but
subsequent market entrants, such as fast packet systems, have
made ISDN less appealing where raw throughput is required.
ISP:
Internet Service Provider. In orer to get access to the Internet,
you need to connect to a system that is already on the Internet.
For many people, this is one of the major online services such as
CompuServe or America Online; for others, it is a local Internet
company. All of these companies are called Internet Service
Providers, or ISPs, because they provide you with Internet
service, similar to the way the local telephone company provides
you with phone service.
JFIF:
JPEG File Format. File-storage format for images compressed with
the JPEG algorithm.
JPEG:
Joint Photographic Experts Group. Used to refer to the standard
they developed for still image compression, which is sanctioned
by the International Standards Organization (ISO).
LAN:
Local Area Network. A network of computers and peripherals that
spans a small physical area, usually one building or a small
campus.
MAM:
Metropolitan Area Network. A network that covers a city (tens of
miles) and operates at data rates similar to a LAN. Usually owned
by service companies that resell the data service to end-users.
megahertz:
Abbreviated MHz. The unit of measure that describes the rate at
which computers operate. A rough guide to computer performance,
but not always accurate for comparing capabilities of dissimilar
computers.
MIME:
Multipurpose Internet Mail Extensions. A standard for embedding
multimedia din in e-mail messages. Regular mail can only contain
ASCII characters because of the limitations of SMPT, the protocol
used to pass mail between Internet computers. In the past few
years, this limitation has become a major problem as more people
want to pass pictures, sound and formatted text. To address these
problems, a new standard called MIME was developed. MIME allows
arbitrary data to be included in mail messages, as long as the
header in the mail message identifies the content so that the
mail client can read it. In order to use a message with MIME
content, you need a mail client that has MIME capabilities. The
Unix mail program, mail, doesn't have these capabilities, but
most other modern mail programs do. Note that some mail readers
support more MIME capabilities than others. For example, elm and
Pine are character-based programs, so they don't support
displaying pictures or playing sounds; however, they do support
reading messages that use the MIME standard for breaking a
message into separately-readable parts. MIME has other features
that will help establish it as the standard protocol to use in
the future. For example, you can add formatting (such as bold and
italics) to your plain text messages; you can break a single
message into many parts so that the reader can skip parts he or
she is not interested in; you can send video segments; and you
can even define your own type of data (such as a new kind of
picture file) for inclusion. As more people create MIME-enhanced
messages, there will be more demand for MIME-compliant mail
readers. Within a few years, it will be normal to get voice- and
video-mail over the Internet as easily as text mail.
MO:
Magneto-optical technology combines an optical laser with a
magnetic field to read and write data on a coated glass or
plastic disc. MO storage is well suited for photographic storage.
modem:
A hardware accessory needed to link two computers via the
telephone system.
NETBIOS:
Network Basic Input/Output System. A standard for supporting
network communications that is independent of the underlying
network transport type.
packet switching:
Units of information with headers that may travel individually or
in groups on a network.
parallel interface:
An interface between a computer and a printer that enables the
computer to send multiple bits of information to the printer
simultaneously.
peer to peer:
A network system consisting of workstations that are capable of
being both server and client.
PICT:
Macintosh Picture. A storage format for digital images designed
primarily for the Macintosh.
pixel:
The picture elements that make up an image, similar to grains in
a photograph or dots in a half-tone. Each pixel can represent a
number of different shades or colors, depending upon how much
storage space is allocated for it.
POP:
Point of Presence. As more people want to get on the Internet,
many providers have set up systems throughout the country.
Because high-speed networks are much less expensive to run than
they used to be, there is often no advantage to having your
Internet provider be in your same city. As long as there is a
high-speed connection from where you are to the host site, a
long-distance works just as well. You may be in New York and your
Internet provider's computer may be in California, and the
distance would be invisible to you as long as there was a local
phone number to call. A point of presence is a bank of modems in
a city that is connected through a high-speed connection to the
site of the host computer that is connected to the Internet. To
the users in that city, the Internet provider has a local
presence, even if it is illusory. Some providers have points of
presence only in nearby cities; others have points of presence
across the country.
PPP:
Point-to-Point Protocol. An Internet standard providing direct
connections through telephone lines.
port:
An interface that controls the flow of data between the central
processing unit and external devices such as printers and
monitors.
RAID:
Redundant array of independent drives storage solutions vary from
a simple enclosure of drives, power supply and fan to a modular
tower of drives, power supplies, fans and a multitude of
high-tech bells and whistles. These are considered most ideal for
work-in-process situations. A data management trend today is
combining CD-ROM, MO, DAT and DLT technologies with RAID
utilization for a more panoramic data management horizon.
resolution, image:
Number of pixels (in both height and width) making up an image.
The higher the resolution of magimage, the greater its clarity
and definition.
resolution, output:
The number of dots per inch, dpi, used to display an image on a
display device (monitor) or in print.
RGB:
Red Green Blue. An additive system for representing the color
spectrum using cominations of red, green, and blue. used in video
display devices.
router:
A device that links networks that are running different
protocols. It can be used to separate unwanted traffic on either
side of the bridge, to reduce the traffic, or to provide security
from unwanted users.
SCSI:
Small Computer System Interface. A high-speed port used to
connect computers with printers and other peripherals.
server:
A PC dedicated to one or more particular services on a network.
SGML:
Standardized General Markup Language.
SLIP:
Serial Line Internet Protocol. An Internet standard providing
direct connections through telephone lines.
smtp:
Simple Mail Transfer Protocol is designed for sending text
messages. This means anything with more complex data (program
files, digitized voice messages, graphics and so on) has to be
encoded into a simple text version before transmission. Each
piece of mail is simply a text file that includes the addressing
information and the message itself.
software:
System, utility, or application programs expressed in a
computer-readable language.
SQL:
Structure Query Language. A data-sorting language, used as a
front-end or client to make requests of a relational database
service.
T1:
Common for links between Internet servers: roughly 1500kbaud, or
12 times faster than fast ISDN.
T3:
The speed of much of the Internet backbone; roughly 25 times
faster than T1.
TCP/IP:
The Transmission Control Protocol/Internet Protocol architecture
is a collection of standards that was developed in 1969 on a
network called ARPANET (Advanced Research Projects Agency
Network) to prove the feasibility of wide-area networking. The
protocols and ARPANET were so successful that TCP/IP can be found
on a wide range of LAN systems, and ARPANET has grown into what
is now called Internet.
telnet:
A remote terminal program that enables you to sit at one computer
and run programs on another computer. The screen data from the
program on the remote computer is displayed on your screen, and
the data you type on your keyboard is sent to the remote
computer. This is efficient if you're running programs that
access large amounts of data on a remote computer. Rather than
running the program locally on your machine and hauling the data
from the remote company across the network (which could be very
time-consuming and would consequently reduce the available
network capacity for other users), telnet lets you work on the
data where it is (remotely) and use the network to control the
access and transfer the results.
Token Ring:
A network transport technology in which a token is passed around
in a ring topology, transferring data at either 4 or 16 Mbit/s.
Unix:
An operating system.
UPS:
Uninterruptible Power Supply. A backup unit that provides
continuous electrical power when the normal power supply is
interrupted.
URL:
Uniform Resource Locator. The way you indicate where you are
going on the World Wide Web is with URLs (Uniform Resource
Locators). URLs are similar to postal addresses or telephone
numbers: you can use them to identify the end point of what you
want. Most URL's consist of three parts: the service name, the
host name, and the request. For example, a typical URL looks
like:
http://www.newsoft.com/internet/paml/:
In this URL, ``http:'' is the service name, ``www.neosoft.com'' is the host name, and ``internet/paml/'' is the request. It is common to have URLs where the request is just a single ``/''. The most common service names you see in URLs are ``http:'', `gopher:'', ``ftp:'', and ``news:''. These refer to Web servers, Gopher servers, FTP servers, and Usenet news servers, respectively. A few URLs do not have a host name. The only ones of this type that you normally see are mailto: URLs that give an email address such as: mailto:chrisr@english.small.edu
VGA:
Video Graphics Array. The 8-bit graphics standards for video
output on PCs, which feature 640 x 480 resolution and 256 colors.
WAN:
Wide area network. Any network that covers a wide area and
requires special communication devices to make connections
possible. The largest differences between WANs and LANs are the
need to make connections over long distances and the need for
telephone, satellite, or microwave equipment to facilitate the
connection.
x86:
A series of microprocessor chips manufactured by Intel. They
range from the older, less powerful 286 and 386 chip ๘he the
more recent and more powerful Pentium and Pentium Pro.