ACCC Glossary of Computer Terms, O-S

Contents

O | P | Q | R | S

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List of Defined Words

OC3, OC12
Offline
Online
Operating System
Orphans
Output
Overlay
Package
Packet
Page Description Language
Page printer
Parallel communication
Parallel processing
Parity Bit
Parity Check
Pascal
Passthrough
Password
Peer-to-peer computing
Peripherals
Personal Computer
PF Key
ph (phonebook)
Phototypesetting
Pica
Pine
PING
Pitch
Pixels
PL/I
PLATO
PNS
Point
POP
POP account
Port
Portrait printing
Post Processing
PostScript
PPP
Print server
Proportional Fonts
Protocols
PVC
PVP
QoS Quality of Service
QuickTime
RAM
Random Access
Recto page
Required Blank
Resolution
Response Time
RFC
RGB
RIFF
ROM
Router and Routing Table
RPC
RS-232
Sans Serif
SAS
SAS/Graph
SCA
SCRIPT
ScriptX
Sequential Access
Serial communication
Serif
Server
Service Unit (SU)
SGML
Shared File System (SFS)
Simplex
SIMSCRIPT
Site
SLIP
SMTP
SNA
SND
SNOBOL
Software
Software Package
Spooler
SPSS
Standard
StarLAN
Start bit
Statistical multiplexing
Stop bit
Store and forward
Story board
Style
Supercomputer
SuperWylbur
SVC
Switched ethernet
Synchronous transmission
SyQuest
System Crash 

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OC-3, OC-12

Optical Carrier (level): OC3 can carry up to 155 Mbps and OC-12 622 Mbps. OC3 is the base; higher transmission speeds (which run on different types of wires) are obtained by sticking multiple OC3 cells together. OC-12 and OC-12c differ in how the "sticking together" is done.

Offline

Logically or physically disconnected from the computer. For example, a reel of tape is offline storage.

Offline

Logically or physically disconnected from the computer. For example, a reel of tape is offline storage.

Online

Connected and accessible to the computer. For example, most disk storage at UIC is online and is therefore easily and quickly accessed.

Operating System

The controlling program(s) that oversee the operation of the computer. Some operating system functions are job scheduling, low level input/output handling, and job accounting. Often abbreviated as "o/s".

Orphans

A text formatting term: The first line of a paragraph is called an orphan when it is separated from the rest of the paragraph by a page break. See also Widows.

Output

(1) Data transferred from a computer's internal storage unit to some storage or output device. (2) The final result of data that have been processed by the computer or a particular computer program.

Overlay

A text formatting term: A predefined graphic overlay form, which is stored on the printer and which may be printed on an output page, independent of any other text or graphics on the page. The must common use of an overlay at UIC is to print a departmental letterhead. Departments may contact the ACCC to arrange to have a letterhead overlay developed for their departments.

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Package

See Software Package.

Packet

The unit of data sent across a network -- a sequence of bits including data and call control signals (headers), arranged in a specific format, which is sent (switched) together as a single identity. Also known as frame, datagram, segment, or message, sometimes with a little different meaning. Sometimes "packet" is used more specifically to refer to a unit of data on a physical network.

Page Description Language

A text formatting term: In desktop publishing, a program that allows you to use a microcomputer to describe to a printer the graphics elements used in page layout and design. Adobe PostScript is the de facto standard of page description languages.

Page printer

A text formatting term: A printer which prints an entire page at a time, as opposed to a line printer, which prints pages (even graphics) one line at a time. At UIC, the ACCC's Xerox 8790 and 4045 printers are page printers.

Parallel communication

A form of computer communication in which data is transmitted using parallel electronic paths. See also serial communication.

Parallel processing

The ability to process "chunks" or blocks of a program simultaneously. To do this, the computer has to have several CPU units and the software to coordinate them, or it must be able to simulate such a situation.

Parity Bit

An extra check bit added to the binary representation a character to make it conform to the parity checking method used.

Parity Check

A method of error detection that checks whether the sum of bits in each character received conforms to a given protocol. In odd parity, the sum of the bits (including the parity bit) must be odd; if a pattern would otherwise be even, the parity bit is set to 1 to maintain oddity. In even parity, the opposite convention is used. In mark or no parity, no parity checking is done.

Pascal

A modern block-structured programming language, with a simple and well defined syntax. Pascal was designed to be a simple language for teaching purposes, and is widely used as such. See Programming Languages at the ACCC.

Passthrough

A software facility which, when used during an interactive computer session, allows you to open another session on the same or a different computer, while keeping your original session.

Password

All computer subaccounts must have a private password to identify the account's ownership when logging on. See the ACCC Accounts, Machines, Passwords page.

PCX

Graphic format originally used by PC Paintbrush; the newest version supports 8-bit and 16-bit color images; supported by most PC and some Mac graphic programs.

PDF Portable Document Format

A platform independent PostScript-based file format; part of Adobe Acrobat.

Peer-to-peer computing

As opposed to client-server computing, in peer-to-peer computing, each network device runs both the client and server portions of an application. See also client-server computing.

Peripherals

Any device which is attached to a computer system or LAN. Devices such as printers, disks and tape drives which are often attached to computers or LANs.

Personal Computer

See Microcomputer.

PF Key

A CMS term: Program Function Keys; keyboard shortcut keys for VM/CMS.

ph (phonebook)

ph is a phonebook protocol which was developed at UIUC. UIC, as well as many other universities, uses ph for their online phonebook. See Using the UIC Phonebook.

Photo CD

Kodak's technology for storing images on CDs, in five resolutions, for printing, computer display, HDTV display, and thumbnails.

Phototypesetting

A text formatting term: Producing a page image on photosensitive paper, as when documents are printed on a Linotronic 100 or 200 typesetter. This process is sometimes referred to as cold type to distinguish it from the older method of casting characters, lines, or whole pages in lead, which is called hot type.

Pica

A text formatting term: A unit of measure equal to 1/6 inch, or 12 points. Pica is also used to describe a font which is 10 characters per inch.

PICT

A Macintosh graphic image format; the newest version can be compressed and supports 24-bit color images; supported by most Mac and PC graphic programs.

Pine

Eudora is an email reading program, one of three that are supported by ACCC at UIC. (Eudora for Windows and Macs and WebMail for any Web browser are the other two.)

PING

Packet INternet Groper: The ICMP (Internet Control Message Protocol) provides message packets to report errors and other information in IP processing; PING uses ICMP echo messages and its reply to test the reachability of a network device. See Using Ping.

Pitch

A text formatting term: The unit of measure for the size of (fixed width or mono-spaced) fonts; it is equal to the number of characters which will print in an inch; e.g. a 12-pitch type prints twelve characters per inch. Also known as CPI (characters per inch).

Pixels

See Resolution.

PL/I

Programming Language One: A high level programming language written to be applicable in arithmetic, scientific and business environments.

PLATO

An interactive educational computer system using text and graphics to teach a wide range of subjects. An example of Computer Assisted Instruction.

PNS

Personal Name Service: An electronic mail alias service which allows personalized aliases for electronic mail addresses. Every faculty and staff member who is included in the online faculty/staff directory database may select a PNS alias from a set of suggested aliases, all of which are based on his or her full name. (At UIC, PNS aliases must must follow some general guidelines which ensure their uniqueness.)

Point

A text formatting term: The smallest unit of measure in typographic measurement. There are 12 points in a pica, and 72 points in an inch.

POP account

See Email account

POP

Post Office Protocol: A client-server protocol which allows electronic mail be retrieved from a server to a personal computer. Eudora (for Windows and Macs) is an example of email client software that uses POP.
Also, in networking, Point Of Presence; a geographic location where a network, leased line, or even dialin lines can be connected to a network.

Port

A pathway for data flow in and out of a computer. On PCs, a port is a slot or plug where cables for input and output devices are attached.

Portrait printing

A text formatting term: The normal printing orientation for a page, i.e., printing horizontal text across the 8.5 inch dimension of a 8.5 by 11 inch page. See also Inverse Portrait, Landscape, and Inverse Landscape printing.

Post Processing

A post processing program process the output from another program. The most common use of a post processor is with systems which have one general program which processes user input and generate generic output, which contains no system or device dependent information. This device independent output is then passed to a post processor which creates final output which is specific for a particular machine or output device.

PostScript

The de facto standard page description language (PDL). PostScript is the page description language used by the Apple LaserWriter and other high resolution printers and typesetters. Internet.com's PC Webopedia has a nice article on PostScript, which includes links to several other, more detailed articles on PostScript.

PPP

Point-to-Point Protocol, defined in RFC 1171, provides a method for transmitting packets over serial point-to-point links. See internet.com's PC Webopaedia entry on PPP, the Network Service Kit, and the NETNEWS/Usenet PPP FAQ. See also: SLIP.

Print server

Like a file server, a print server allows the machines on a LAN to share a single printer and also handles the printing queue for the printer.

Proportional Fonts

Printer type styles in which each character occupies a different width in the output line, depending on the actual physical width of the character. Thus, in a proportional font, the character "i" is much less wide than the character "w".

Protocols

A set of rules or procedures implemented in both hardware and software to facilitate communications provide a well defined interface between different systems. The protocol govern format, timing, sequencing, error handling. A converter is device which translates one to another.

PVC

Permanent Virtual Circuit; a virtual link across an ATM network between two specified end points; PVCs are permanently defined by the network manager. PVCs are the ATM equivalent of a leased telephone line. See also SVC. For more information on PVCs and on ATM in general, see the A3C Connection article on ATM: Building the Data Highway.

PVP

Permanent Virtual Path; a set of PVCs. For more information on PVP and on ATM in general, see the A3C Connection article on ATM: Building the Data Highway.

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QoS

ATM networking's Quality of Service parameters; For more information, see the A3C Connection article on ATM: Building the Data Highway.

QuickTime

System-level software architecture supporting time-based media, giving a seamless integration of video, sound, and animation. For Macs and Windows.

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RAM

Random Access Memory: The memory that is available on a computer for storing data and programs that are currently being processed. It is automatically erased when the power is turned off. Information in the RAM which needs to be stored for future use must be saved onto a disk or a tape. See also ROM and memory.

Random Access

The process of selecting information in a arbitrary order, not based on the physical order or sequence of its storage.

Recto page

A text formatting term: The right-hand page of a duplex printed document with facing pages. See also verso page.

Required Blank

A text formatting term: A blank or space which is processed by a word processing package in a slightly different manned from a normal blank. Required blanks print as blanks, but a line break cannot occur at a required blank, nor will additional space be added at a required blank to justify a line of text. The symbol   is used in HTML to indicate a required blank.

Resolution

A text formatting term: The number of dots per inch used to represent a graphics image. The term "pixels" is also used for "dots" in this context. High resolution images look smoother and have more dots per inch than do low resolution images. The resolution of images displayed on the screen is usually lower than that of the final laser printout. Laser printers print 300 dots (or pixels) per inch or more; typesetters print 1,200 dots (or pixels) per inch or more.

Response Time

The time measured from when you enter a command until you receive a response at the terminal.

RFC

Request For Comment: The Internet network standards are called RFCs. A proposed Internet standard is initially issued as a proposal, and given an RFC number. When it is finally accepted, it is added to Official Internet Protocols, but it is still referred to by the RFC number. There's more on Inform; do a keyword search for RFC.

RGB (Red Green Blue)

The additive colors used by computers to display colors. White is 100% of all three colors, black is 0% of all three.

RIFF Resource Interchange File Format

A file format for multimedia data on PCs; can contain bitmapped graphics, animation, digital audio, and MIDI files

RJE

Remote Job Entry: Refers to an application which is batch rather than interactive. In RJE environments, jobs are submitted to a computing facility and output received later.

ROM

Read Only Memory: Stored permanent systems instructions which are never changed; ROM is generally installed by the manufacturer as part of the system. See also RAM and memory.

Router and Routing Table

A special-purpose dedicated computer that attaches to two or more networks and routes packets from one network to the other; also known as gateways. In particular, an Internet gateway routes IP datagrams among the networks it connects. Gateways route packets to other gateways until they can be delivered to the final destination directly across one physical network. A routing table is a table stored on a router or other internetworking device which keeps track of routes to particular network destinations.

RPC

Remote Procedure Call: the basis of distributed (client-server) computing. Remote procedure calls are specified by clients and executed on servers, with the results returned over the network to the clients.

RS232

A standard connection for serial computer communications as described by the Electronics Industry Association (EIA). The standard specifies the physical connections between computers and other devices, such as modems and printers and defines characteristics of the electrical signals sent through the connection. See the EIA home page and internet.com's PC Webopaedia entry for RS232

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Sans Serif

A text formatting term: Type styles without serifs, such as Helvetica, Avant Garde, and Geneva. See also Serif.

SAS

(Formerly Statistical Analysis System) A software system for data analysis. SAS is available on ACCC UNIX and on the public personal computers. SAS provides tools for information storage and retrieval, data modification, report writing, file handling, and statistical analysis. SAS/Graph provides a complete graphics system, for plotting on a variety of printers and graphics terminals. SAS includes interface routines for linking with the other available statistical packages. For more information, see the ACCC Statistical Resources and Information page.

SAS/Graph

The graphics portions of the SAS statistical analysis system.

SCA

The Scientific Computing Associates: Although SCA can be used for general statistical analysis, it is mainly a package for time-series analysis. For more information, see the ACCC Statistical Resources and Information page.

SCRIPT

Waterloo SCRIPT is one of the word processing packages that was available on UICVM.

ScriptX

An object-oriented authoring language and multi-platform standard for multimedia software development.

SCSI Small Computer Systems Interface

A fast general-purpose system interface for connecting computer peripherals such as hard drives, scanners, printers, CD-ROM drives, and so on.

Sequential Access

Reading data from a file whose records are organized on the basis of their successive physical positions. To reach a specific record, all records previous to that record must be read, in order. Magnetic computer tapes are sequential access storage device.

Serial communication

A form of computer communication in which data is transmitted one bit at a time over a single path. See also parallel communication.

Serif

A text formatting term: A line crossing the main strokes of a letter. Type styles that have serifs include Times, Courier, New Century Schoolbook, Bookman, Palatino and New York. See also Sans serif.

Server

Server is a special device used to "serve" some system or facility. A server is usually a microcomputer, or, on CMS, a special account which runs automatically without interactive supervision. Servers act in response to requests which are sent to it.

Service Unit (SU)

A unit of measure for supercomputer use; it equals one hour of Cray X-MP CPU time.

SGML:

Standard Generalized Markup Language. A meta-language for defining markup languages.

Shared File System (SFS)

A file system on CMS that let users organize their files into directory trees.

Simplex

(1) A text formatting term: printing only on one side of the paper. (2) A computer communications term: Simplex data transmission is in only one direction.

SIMSCRIPT

A higher level language designed specifically for simulation.

Site

An organization or facility where a host computer is located.

SLIP

Serial Line Internet Protocol: SLIP is currently a de facto standard, commonly used for point-to-point serial connections running TCP/IP. It is not an Internet standard but is defined in RFC 1055. See internet.com's PC Webopaedia entry on SLIP and the Network Service Kit. See also PPP.

SMTP

Simple Mail Transfer Protocol: A protocol from the Internet suite (e.g., TCP/IP) that is used to send electronic mail between users on different host systems. SMTP is defined in the Internet RFC 821. For more information on SMTP as it is used at the UIC, see Changing to your ISP's SMTP server.

SNA

Systems Network Architecture: An IBM developed specification for the logical structure, formats, protocols, and operational sequences for reliable transfer of data among SNA users and applications. SNA also includes specifications for controlling the configuration and operation of a network.

SND

A standard Mac resource format for sounds; now widely supported.

SNOBOL

SNOBOL4 is a programming language developed at Bell Telephone Laboratories. It is designed to be especially useful when processing character-string data in complex ways.

Software

The programs and data that make computer hardware function.

Software Package

A program or set of programs that usually perform a specific function. Programming (i.e., the development of a computer program in some higher level programming language) is generally not necessary when using a software package; specialized statements and/or data are used instead. SAS and SPSS are examples of statistical packages.

Spooler

A program which manages requests or jobs submitted to it for execution, selection requests for execution in an orderly manner from a queue. Print spoolers are a common example.

SPSS

Statistical Package for the Social Sciences: A software system for data management and analysis. SPSS may be used for many univariate and multivariate statistical analyses and has facilities for sorting and merging files and manipulating data. SPSS can deal automatically with complex files. For more information, see the ACCC Statistical Resources and Information page.

Standard

A set of rules or procedures, either commonly used (de facto standards) or set by official decree (de jure standards).

StarLAN

A LAN developed by AT x (IEEE 802.3 1Base5.A standard).

Start bit

A signal, usually a binary "0", used to alert to the receiving machine the beginning of a byte of data.

statistical multiplexing

ATM networking: If bursts of data result in more data being put on an ATM network than it can handle at one time, the excess data is buffered and put in subsequent free cells. This allows the peak bandwidth on ATM networks to be higher than the network's physical media can carry. The network's administrators use "statistical" estimates to decide by how much they can oversubscribe the network's total bandwidth. (In other words, they hope that simultaneous multiple bursts like this will be statistically unlikely.)

Stop bit

A signal, usually a binary "1", sometimes used to indicate the end of a byte of transmitted data.

Store and forward

A message switching technique in which messages are temporarily stored at intermediate points between the source and the destination until the required network resources are available. BITNET (CREN) was a store and forward network; the Internet is not.

Story board

A precise description detailing how each multimedia element is going to be used and screen-by-screen planning of what is available to the end user.

Style

A text formatting term: The overall appearance of a font is referred to as the style. The type styles have names, such as Helvetica, Courier, and so on. (Note: there is some disagreement on the usage of this term; sometimes "style" is used to refer to the degree of boldness or slant of a particular font within a family [e.g., Bold], which is more commonly referred to as the typeface.) See also typeface.

Synchronous transmission

a method of data transmission in which characters are sent at a fixed rate, with the transmitter and receiver synchronized.

Supercomputer

A large mainframe computer; usually reserved for computers with the fastest speeds and largest memory. These computers usually have an architecture that is different from regular mainframes. The main difference lies in the ability to perform vector and/or parallel processing. One might say that ACCC's borg.uic.edu is a supercomputer, but it's really just a pretty good compute server.

SuperWylbur

A very long ago, but very good for its time, mainframe line-at-a-time text editor.

SVC

Switched Virtual Circuit; a virtual link across an ATM network; unlike a PVC, the endpoints in an SVC are specified by the user when the connection is made. Also, SVP, Switched Virtual Path, a set of SVCs. See also PVC.

Switched ethernet

ATM networking: a simple way to improve LAN performance by attaching desktop machines to a specialized switch that talks ethernet on one side and ATM on the other, making them think they each have their own ethernet network.

System Crash

A breakdown of either the operating system or the hardware, resulting in the system's halting, often very abruptly, and throwing its users off. Software packages have also been know to crash, sometimes taking the operating system along with them.

SyQuest

An older but proven removable data storage technology in 44MB, 88MB, and 200MB 5.5 inch cartridges or 105MB and 270MB 3.5 inch cartridges. Initial cost is much lower than for MO drives.

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