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The Metacomputer: Glossary of Terms
- The type of job performed by a computer or system of computers. Examples of applications include: climate modelling; molecular dynamics; airline scheduling;
- A set of rules or procedures by which a computer solves a problem in a stepwise
- A term used to describe the design of processors, both individual and
in general. It may also be used to describe any complex system, eg.
"software architecture", "network architecture".
- Andrew File System (AFS)
- A type of file system which is not dependent on any one computer to
hold its files. With AFS, a user can login to any computer within the
AFS environment and access his/her files, regardless of which computer
actually stores the files. AFS is therefore a distributed file system.
- Asynchronous Transfer Mode (ATM)
- A networking medium which uses a fixed-size packet,
called a cell, to transfer data. ATM can handle the "high
bandwidth" requirements of multimedia data transmission (video and sound
data use an extremely large amount of bits).
- Refers to how much data can be sent through a connection, usually measured
in bits-per-second. The more bits-per-second, the "higher"
- The smallest bit of information in a binary encoding system, either a 1 or 0.
- A common pathway that connects the parts of computer system and through which data in the form of electrical signals is transferred.
- A unit of 8 contiguous binary digits, or bits. A byte represents one character.
- A superset of the C programming language. C++ was developed primarily
to facilitate the management, programming, and maintenance of extremely large sets of C software. C++ is an object-oriented language; it manipulates data sets, or objects, rather than individual numbers.
- A program which reads a source program created by a programmer, and then converts the program into a set of instructions known as the object program, also known as machine code. The object program is in a form that a computer can underst
and and execute directly.
- Compile Server
- A computer connected to a supercomputer, on which source programs for
the supercomputer are compiled. This allows the
supercomputer to use all of its resources for number crunching. The compile server's architecture matches the supercomputer's, so that the compiled object programs are compatible.
- Detecting, tracing, and eliminating mistakes in programs and other
- A flat rotating disk covered on one or both sides with magnetizable
material. Data is stored in concentric rings called "tracks" and read
and written by a disk drive. There are two main types of disk: the hard disk and
the floppy disk.
- Domain Name
- The unique identifier for a computer on the Internet. A domain name
consists of a sequence of names separated by periods. As an example,
"cm5.ncsa.uiuc.edu" is the domain name for the computer cm5 (the cm5
being referred to as the "hostname" corresponding to a Connection Machine 5)
which is housed at NCSA at the University of Illinois at Urbana-Champaign (uiuc).
Each sequence by itself may not be unique, but
when put together is sufficient to assure a unique domain name.
- A network system for local computers that uses a series of standard
network protocols that allow different types of computers to communicate,
at about 10,000,000 bits-per-second.
- Fiber Distributed Data Interface. A standard for transmitting data on
optical fiber cables at a rate of around 100,000,000 bits-per-second
(about 10 times faster than Ethernet).
- File Transfer Protocol (FTP)
- Allows the transfer of files between any machines supporting TCP/IP on a network. FTP provides a limited route by which a user can login to a computer for the sole purpose of retrieving and/or sending files.
- Floating point operations per second. A measure of how fast a computer
is based on calculations per second. A floating point is a number
representation consisting of a mantissa, an exponent, and an assumed
radix. The number represented is M multiplied by R raised to the power of E (M*R^E) where R is the radix or base of the number system. (For example, 10 is the radix of the decimal system.)
- Fortran stands for FORmula TRANslator, the first and still the most widely used
programming language for numerical and scientific applications.
Popular versions include Fortran 77 and Fortran 90; some versions,
such as HPF, have been developed to run on parallel
- 10^9 power. A gigabyte is 1,073,741,824 bytes, or roughly a billion
- High Performance Parallel Interface. HIPPI is a simple point-to-point
unidirectional connection for data transmission at speeds up to 800 Mbits/second on
a single cable. HIPPI is normally (but not necessarily) deployed in
pairs in order to achieve a full duplex connection (one that can allow simultaneous
transmission in both directions).
HIPPI cables are
limited to 25 meters by physical limitations, but repeaters can be
used to connect cables together as well as extenders that work to
extend HIPPI over fiber up to 20 kilometers. A HIPPI interface is
commonly used to connect together a group of computers in close
proximity, allowing very rapid transfers of data.
- High-performance Fortran (HPF)
- An extension of Fortran 90 which supports data
- 1) A network interface is the software that handles machine to machine
- 2) A user interface refers to the aspects of a computer system or program
which can be seen by the user, and the commands and mechanisms used to control
a computer's operation and input data.
- Load Balancing
- Techniques which aim to spread tasks among the processors in a
parallel processing system in order to avoid some processors
standing idle while others have tasks queueing for execution. Load balancing may
be performed by (a) heavily loaded processors sending tasks to other
processors; (b) idle processors requesting work from others; (c)
some centralized task distribution mechanism; or (d) some combination
of these options.
- A large computer that can handle many tasks and multiple users at the
- A million, in reference to computing. A megabyte is a million
bytes or a thousand kilobytes.
- Message Passing Interface (MPI)
- A "translator" language that allows different types of computers or processors to communicate and share tasks. Think of MPI as "computer Esperanto."
- Network Protocol
- A formal description of message formats and rules that two or more
computers must follow in order to communicate across a network.
- In networking terms, an individual computer within a network that can
communicate with other computers in the network. Also, refers to an individual
processor within a multiprocessor machine which can communicate with other
processors within that machine.
- Object-oriented (Programming)
- An method of programming that depends on sets of data objects, each capable of responding to a group of commands targeted at it.
- Operating System
- An integrated collection of programs that controls the execution of
computer programs and performs system functions. Examples include VMS, DOS,
UNIX, DOS, O/S 2, etc.
- A unit of data sent across a network is referred to as a packet. Apart from
data, each packet possesses routing and error-control information.
- Parallelizing Code
- The process of dividing the overall problem into separate tasks
and allocating tasks to processors. This may be handled implicitly
by the operating system, or explicitly by the programmer, where the
programmer must annotate his program to show how it is to be
- Parallel Processing
- The simultaneous use of more than one computer or processor to solve
a problem. The processors may communicate in order to be able to
cooperate in solving a problem or they may run completely independently,
possibly under the control of another processor which distributes
work to the others and collects results from them.
- 10^15 power. A petaflop is a thousand trillion floating
point operations per second, or a thousand teraflops.
- A system or device that can carry out operations on data.
- Round Robin (DNS)
- A load balancing technique, where a group of computers take turns using
a single domain name.
- A program designed on a workstation and can also be run on a larger
machine (such as a supercomputer) is said to be scalable. Also, a
computer to which more processors, disk drives, etc. can be added is
referred to as scalable.
- Shared Memory
Memory in a parallel computer, usually RAM (Random Access Memory - the "working memory" of the computer) which can be accessed by
more than one processor, usually via a shared bus or network.
- Instructions or sets of instructions, also called a program, that directs a computer's handling of data.
- Transmission Control Protocol/Internet Protocol (TCP/ICP)
- Each term refers to a standard for software to control communications between
computers on interconnected networks, particularly the Internet. A protocol is a set of rules controlling how computers communicate with eachother.
- 1) Networking protocols are said to be transparent
when not perceived in using a remote computer; instead, the user's
perception is that of being directly linked to the remote computer, as if
it's an integral part of his or her own computer.
- 2) In the context of "metacomputing," computers and other types of
equipment may be separated by thousands of miles, yet they appear
to the user interface as one system. This type of
transparency depends heavily on very fast networks to prevent any time lag.
- In computing, a trillion. A terabyte is one trillion bytes.
- Vector Processing
- Calculations are performed in linear, assembly line fashion. Each
processor carries out a mathematical step on a piece of data before
handing the data off to the next processor.
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NCSA. Last modified, 10/21/95