a semi-precise and somewhat biased explanation of some computer terms...

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

- A -

The DEC Alpha is the world's fastest microcomputer chip. Alpha CPU's are 64 bit RISC chips available in speeds up to 500MHz.
Any system of measuring, representing, or communicating data that relies on a proportional and continuous representation of possible states. The indicating needle on a pressure gauge is a type of analog system. The needle moves a distance that is continuously proportional to changes in pressure. Ordinary telephone systems are analog in that the signal voltage changes continously in proportion to the loudness and frequency of the audio. opposed to 'digital.'
Apple Computer
One of the longest-lived manufacturers in the microcomputer industry. The first Apple computers appeared in the 70's and used a version of the 8-bit Signetics microprocessor chip. See Intel.
Network Address Resolution Protocol. Used to convert between IP layer and Ethernet layer data encapsulation. See RARP.
American Standard Code for Information Interchange, usually pronounced 'as-key.' ASCII is an 8-bit code which means it can have 256 possible values. This code has standard numerical values assigned to various characters and control functions, for example in ASCII A=65, B=66, C=67, ... a=97, b=98,... 1=49, 2=50,... 'space'=32, 'carriage return'=13,etc, etc....
AT Computer
IBM's 'Advanced Technology' computer contained the Intel '286 microprocessor. AT's are now considered obsolete as they do not have the necessary addressing modes to run Windows 95. The original AT's ran at less than 10MHz although later versions were capable of 16 or 20. AT's were 16-bit computers meaning that they moved data that was 2 bytes wide. Previous Intel processors had 8-bit data paths. You can start an argument in some circles by claiming that the AT was Intel's first 32-bit computer since it had some 32-bit data registers.
Back to Top

- B -

A computer language for writing and executing programs. Stands for Beginner's All-purpose Symbolic Instruction Code. Basic was invented at Dartmouth College in the '60's to introduce students to computer coding. Much of the early success of microcomputers came from BASIC language programs which proliferated in the early 80's. BASIC has evolved into the graphical computing era so that now we find many Windows programs have Microsoft's Visual Basic language embedded in them and accessible to the user. Visual Basic is extremely powerful and is object oriented in structure. Though easier to use than some more powerful languages such as C++, Visual Basic requires more effort to learn than the earlier versions. Microsoft's QBasic is an updated version of BASIC that is much simpler to use than Visual Basic and can be quite useful for casual programming. QBasic comes with MS-DOS and is used by the EDIT editor.
A single element of data representing one of two possible states, on or off, yes or no, true or false, etc. A bit is usually represented as 1 or 0.
A computer program designed to fetch and display hypertext documents especially web pages. Browsers such as Netscape or Microsoft Internet Explorer (MSIE) are useful for looking around the Internet. You are using a browser or some sort right now to see this web page. MSIE has been distributed at no charge by Microsoft and an upgrade of it is available for download on the PCLES ftp server or over the Internet at '' (look for MSIE download area). Some tips for using your browser on PCLES Web can be found at PCLES Web Tips.
'Blue Screen of Death': Error screen on your Windows computer reporting a fatal error. Usually caused by configuration error in NT, hardware failures in Windows 95, or just about anything in Windows 3.1x.
An 8-bit computer 'word', enough data space to store a character such a letter, number, or other symbol or enough space to store a number between 0 and 255. Bytes of data are often encoded using ASCII.
Back to Top

- C -

Cat 5
Category 5: standard type of twisted pair cable used for 10baseT and 100baseT Ethernet wiring. Has 4 pairs of wires. Cat 5 cables are usually connected with RJ-45 plugs.
C language
Name of a general purpose computer language developed by Dennis Ritchie at Bell Labs in the 1970's. There is an older language called B and a still older coding technique called assembler, or 'A' in the UNIX world. C has the peculiar feature of being a computer program that is written in itself, i.e. C is written in C. C is very 'close' to system hardware in a way that makes it suitable for writing operating system software. Other languages such as FORTRAN are older than C but do not have C's system programming power.
Object-oriented version of the C language. Much more complicated and vastly more powerful than C. Language used by Microsoft to write Windows, Office, etc.
Compact Disk: 5-1/4" diameter laser-writeable media. CD's are written by melting microscopic dots on a layer of a semitransparent plastic disk. Controlling how fast the dot cools determines how reflective that dot is to light. The tiny size of the dots means that a large number of bits can be stored on a CD. First used to as media for audio.
Compact Disk, Read-Only Memory. A CD-ROM is a disk exactly like an audio CD except that it contains software or data for the computer instead of music. A CD-ROM drive is required to use this data. An audio CD player will not work although a computer CD-ROM drive may be used to play audio CD's if the right software and audio board is present. A CD-ROM will hold about 600MB of data. CD-ROM drives are rated by their playback speed, the fastest now are about 20x or 20 times the speed of the original drives. CD-ROM disks are considered 'read-only' although they are really 'write-once, read-many' or 'WORM' media. Although ordinary CD-ROM drives will not write to their CD's, special CDR drives will write once to a blank CD.
Nickname for IC, because an integrated circuit is built on a small crystalline flake of semiconductor material such as silicon.
Nickname for IC, links individual PC's or terminals into a workgroup or domain by authenticating passwords through one or more central server. Such a system holds passwords in a remote system for improved security over a peer-to-peer network. Windows NT Server can be used to control a client-server network where the clients are PC's running various operating systems such as Windows NT Workstation, Windows 95, Windows 3.11, MacIntosh, OS/2.
Starting with AT compatible PC's, setup configuration was stored on a non-volatile memory system which was kept active by a small battery. This arrangement was only possible because this type of memory has a miniscule current requirement from the battery. In fact such a circuit made up of Complementary Metal Oxide Semiconductor transistors only draws current when a transistor is turning on or off. When you "set up the CMOS" on a new PC those transistor gates are being programmed. Older terminals that forget their speed and bit settings after you turn them off probably have CMOS that is okay but the internal battery, soldered to the circuit board, no longer holds a charge. Electronic Alzheimers....
Software program specific to a particular computer language that translates human-readable source code into machine code using the instructions of a specific computer.
A device capable of automatically executing programs. Computers are generally electronic although some specialized devices have been built that are mechanical or use light or even fluids instead of electrical signals. The first electronic computers were built at the University of Pennsylvania in the 1940's and used vacuum tubes as the electronic or 'non-linear' element. The 'mini-computer' of the 1960's such as the first machines made by Digital Corporation used discrete separate transistors for 'non-linear' gates. Companies such as Intel, Signetics, RCA, and Zilog started the 'micor-computer' era in the 1970's by 'integrating' first hundreds and then thousands and millions of transistor circuits on single silicon 'chips'... the integrated circuit or IC microprocessor chip.
computer language
A computer language is a set of words, commands, and codes in human-readable form that a compiler uses to cause the computer to execute equivalent machine-readable instructions. While it is possible to program directly in numeric machine codes it is much faster, simpler, and more reliable to us a higher level computer language. The modern language of choice is C. Other useful languages are BASIC, FORTRAN (FORmula TRANslator), COBOL (COmmon Business Oriented Language), LISP (LISt Processor), Forth, SNOBOL, DIBOL, ADA, PL/I, etc., etc....
"Central Processing Unit" does the calculations in a computer system. The Intel Pentium is an example of a microprocessor chip that is a CPU.
Back to Top

- D -

Information, especially information that has been encoded in a digital format suitable for storage and processing in a computer.
Any system of measuring, representing, or communicating data that relies on coding a state as one of a number of possible states. An 8-bit digital code selects one possibility out of 256. Digital techniques code data to a predetermined resolution and therefore provide precisely controlled error handling. As opposed to 'analog.'
Digital Equipment Corp
Computer manufacturer based in Maynard, Massachusetts. DEC pioneered the minicomputer and now claims the worlds fastest microcomputer CPU the DEC Alpha.
Data storage media usually referring to a hard disk, but can refer to a floppy disk, CD-ROM, DVD, optical, electro-optical, or other exotic devices. Disk drives spin the disk media and read or write data from circular tracks usually with multiple heads.
Disk operating system. Often used as a nickname for MS-DOS. When disk storage first became available in the 1960's disk-based operating systems were distinguished from older batch-load operating systems that ran on punch cards. See operating system.
Copy data from a 'big smart' computer to a 'little stupid' computer , a server to a client, a host to a workstation, a host computer to a dedicated microcontroller, or a remote computer to a local computer. Opposite of upload.
Digital Video Disk. High density disk storage system (similar to CD-ROM but with smaller media) first marketed in 1997. DVD may replace video tape as a medium for storing video and CD-ROM as a medium for archiving data. At this writing the future of DVD is promising but uncertain.
Back to Top

- E -

'Electronic' devices are distinguished from simply 'electrical' devices in that electronic devices have some 'non-linear' components. A non-linear component is something like a semiconductor switch or amplifier or a thermionic emission circuit whose output is not strictly proportional to its input. Semiconductor devices such as transistors and diodes as well as thermionic vacuum tubes are non-linear electronic devices. Non-linearity allows a transistor to amplify by letting a small input signal control a large output current, i.e., an amplifier is an electronic device. If you throw a switch and flick on the lights in a room that is an example of an 'electrical' circuit. If you can slide the lever or turn a knob to dim that light the circuit is probably 'electronic' because there is a triac transistor built into the switch. It is possible to dim the light 'electrically' with a big variable resistor and that would not be electronic, and would waste a lot of energy as heat besides.
One of the original standards for a local area network or LAN. We tend to call our ordinary PC network adapters 'Ethernet cards' although that name is not precisely accurate.
A giga-gigabyte, an NT filesystem can access several exabytes of data.
To run a program in RAM. The computer loads a program into RAM, finds its beginning and then executes it by running through its instruction cycle.
Back to Top

- F -

File Allocation Table, type of filesystem used in MS-DOS computers.
Program or data as it is stored on disk. To run a program you find that program stored as a disk file then run it. The computer copies that program file into RAM and begins executing it. At this point we call the program a process.
Method of storing files on disk. MS-DOS, MacIntosh, UNIX, and NT all use different filesystems. To copy an MS-DOS file to a MacIntosh computer you must translate between these two systems, for example. The filesystem on a disk is defined when that disk is formatted. Hard disks formatted as FAT (MS-DOS) filesystems can be converted to NT Filesystem but not the reverse. UNIX systems usually can write in FAT format to be compatible with other systems. NT knows how to read and write FAT formatted floppies. UNIX filesystem is more secure than FAT by virtue of having more permissions so you can control access that other users have to your files on the network. FAT only has 4 permissions: Read, System, Hide, and Archive. So MS-DOS, Windows 3.x, and Windows 95 all use FAT so you have minimal control over security in these systems. UNIX has Read, Write, and Execute (rwx) but applies these to each of 3 different classes of users: Owner, Group, and World (or Other). UNIX controls system and hide permissions by applying rwx to directories themselves and has no archive code but handles that issue in another way. UNIX is much easier to secure than FAT systems. Windows NT Filesystem has an amazing array of control over how files are used and secured. NT has permissions for Access, Listing, Read, Add, Read & Add, Change, Full Control, or Special access (2 types). Like UNIX, NT allows permissions to apply to individual users, groups of users, or all users, except it uses 9 permissions instead of 3 for each one. Moreover NT allows setting permissions on shared resources with additional Access, Read, Change, and Control options. Moreover NT allow defining of sets of owners for files rather than UNIX's exclusive ownership. Moreover NT allows setting of system policies that customize access to every system resource for individual users or groups. In short, if you have Windows NT Workstation running on your computer with security correctly set up, don't forget your password because no one including you will be breaking into it!
floppy disk
A magnetically recording disk removeable from the computer and useful for backing up or transferring data. The original IBM floppies were about 8 inches wide and were very floppy. These large floppies held only about 240KB of data and needed constant deframentation to make even that small space useable. Smaller 5-1/4 inch floppies came along and held twice as much data which was accessible faster (smaller disk takes less time to come around past the head, significant if the machine is to move thousands of pieces of data per second). Newer 3.5 inch floppies aren't very floppy at all anymore.
File Transfer Protocol Service. Ftp is a way to transfer files or programs from one system to another when these systems share network services. An ftp server is now running on PCLES Web.
Back to Top

- G -

(usually pronounced gig-a-bite, not jig-a-bite) 1 billion bytes, typical size of medium sized PC hard disk.
Back to Top

- H -

hard disk
A non-removeable disk with hundreds or thousands of times more space than a floppy disk. Originally a hard disk was a removeable platter a foot or more in diameter that was stored in a round box like a cake cover. Such disks needed to be handled in a relatively clean environment with air filters and special fans that kept virtually all dust off the spinning disk. Even so the early hard disks held only 5 megabyte or so of data and cost thousands of dollars per year just for maintenance of the fans, filters, etc. Modern hard disk drives are assembled in class-100 or even class-10 laboratory clean rooms (having fewer than 100 or 10 particles per cubic meter which are larger than a millionth of an inch in size). These drives are sealed airtight and typically run several hundred thousand hours before they fail... with no maintenance at all... and they hold a thousand times as much data... and are 1/6th the size...
HyperText Markup Language. The language of web pages. Data in HTML when seen through a web browser has hyperlinks to other points in the web. The page you are reading is written in HTML. The actual code can be viewed by selecting View and then HTML (or Source) from the toolbar above. The code for this page starts out like this....
meta http-equiv="Content-Type"
text/html; charset=iso-8859-1">
meta name="FORMATTER" content="Microsoft FrontPage 2.0">
meta name="GENERATOR" content="Microsoft FrontPage 2.0">
body background="../images/backgrnd.gif">
h1><font color="#0000FF" size="7"><em>Buzzwords<br>
/em></font><font color="#008080" size="3">a semi-precise and
somewhat biased explanation of some computer terms...<
h1><a href="buzzwords.htm#sectA"><font color="#408080"
color="#408080" size="5"><strong> </strong></font><a>
href="buzzwords.htm#sectB"><font color="#408080"
color="#408080" size="5"><strong> </strong></font><a>
href="buzzwords.htm#sectC"><font color="#408080"
color="#408080" size="5"><strong> </strong></font><a>
href="buzzwords.htm#sectD"><font color="#408080"
color="#408080" size="5"><strong> </strong></font><a>
href="buzzwords.htm#sectY"><font color="#408080"
#408080" size="5"><strong> </strong></font><a>
buzzwords.htm#sectZ"><font color="#408080"
#408080" size="5"><strong> </strong></font><a>
buzzwords.htm#sectOther"><font color="#408080"
<h1><a name="sectA">- A -</a></h1>
<dt><a name="Alpha"><strong>Alpha</strong></a></dt>
<dd>The <a href="#Digital Equipment Corp">DEC</a> Alpha is
the world's fastest <a href="#microcomputer">microcomputer</a>
<a href="#chip">chip</a>. Alpha <a href="#CPU">CPU</a>'s
are 64 bit RISC chips available in speeds up to 500<a
<dt><a name="analog"><strong>analog</strong></a></dt>
<dd>Any system of measuring, representing, or communicating
data that relies on a proportional and continuous
It is somewhat tedious to edit pages directly in HTML. It is MUCH easier to use a special web editor such as Microsoft Frontpage to write the HTML for you while you just type in information or drag-and-drop images or other features. All the pages in PCLES Web were generated with Frontpage.
HyperText Transfer Protocol: standard software protocol used for calling up web pages.
Electronic box with sockets for LAN connections in a 10baseT network. Wiring in such a network runs from each computer back to a hub like spokes on a wheel, sometimes called a 'star' configuration.. Some hubs provide routing of data within the network to reduce errors and transit time (see router). 10baseT sockets are called RJ-45 connectors and look like an 8-pin telephone jack. Some hubs have BNC or AUI sockets for use with 10base2 or 10base5 backbones or to 'stack' several hubs together. See terminal.
Words in a document such as a web page which contain links to other documents or resources. See HTML.
Back to Top

- I -

Semiconductor integrated circuit having typically a postage-stamp size carrier containing a quarter-inch wide wafer of silicon with etched patterns containing various electronic circuits. IC's can have various electronic functions including amplifiers, digital gates, timers, and CPU's. Usually an IC is mounted on a pc board containing other circuits and connectors needed to make up a functioning device.
Every computer has a list of basic instructions (an instruction set) it can execute. A program is nothing more than a sequence of these instructions. For every instruction there is a unique numerical code that the computer knows how to execute.
instruction cycle
To execute an instruction the computer must go through a standard sequence of steps. 1. fetch the instruction code from memory, 2. decode that instruction, 3. fetch the operands, 4. perform the operation, 5. store the results, 6. update the address of the next instruction to fetch, and 7. do it again. You can think of this as the instruction cycle of the particular machine. A '386 and a '486 have similar instruction sets and similar instruction cycles so a program written for a '386 computer will almost certainly run on a '486 or a Pentium. However such a program will NOT run on an Apple computer or a Sun Microsystem machine, say, because their instruction sets are VERY different from each other. This has been a big problem for users of Apple computers now that Intel-based Windows computers have virtually taken over the small computer market.
One of the most successful computer chip makers. Intel Corporation developed one of the first true integrated microcomputer circuits in the early 70's: the 8008. Most Intel chips have followed this 80--- naming scheme until recently. The first 'real' 8-bit micro was the Intel 8080, then came the 8086, the 80286, (yes there was an 80186 that was mostly used in systems like disk controllers), the 80386, and the 80486. The original IBM PC had an Intel 8088 chip, a brain-dead version of the 8086. The '286 was a successful 16-bit computer and found its way into systems such as the IBM-AT personal computer. The '386 chip has 32-bit internal registers and offered a flat addressing mode that permitted huge increase in memory. The '486 chip gave us some multitasking hardware and more addressing modes. Intel decided not to try to have a battle over whether a number could be copyrighted and so renamed the 80586 as the 'Pentium' so strictly speaking there is no '586 chip. Of course everyone calls competitors chips 'Pentiums' even though comparable chips such as the AMD version of the Pentium are more correctly called 'K-5' chips.
The world wide interconnection of networks with standardized unique addressing (see TCP/IP). The Internet is overseen by an organization called INTERNIC. The Internet evolved from an inter-university system called BITNET which evolved from the DOD's Advanced Research Projects Agency Network or ARPANET. Now DARPANET is separate from the Internet for security reasons.
A network of networks within an organization such as the PCLES web
Back to Top

- J -

Computer engineer's late-night-high caffeine beverage of choice. Software engineers have been known to freeze cans of the evil substance to concentrate the caffeine even more. An acquired taste I am told.
Back to Top

- K -

kilo-bits-per-second, a measure of transmission speed in a digital communication circuit. A medium speed computer modem would have a transmission speed of 28.8kbs. The fastest modems have double this speed.
Back to Top

- L -

Local Area Network, used to connect computers within an office or building complex. Computers in a LAN are directly connected with data cables as opposed to a WAN which uses some third-party leased lines. To create a LAN you need to put a network interface card, a NIC, in each computer and cable them together in some way. Ethernet is the name for a LAN running one of the common protocols and can be implemented either as a daisy chain of PC's threaded along a coaxial cable (10base2) or as an array of Twisted pair connections from a central hub (10baseT). 10baseT is the most common setup, 100baseT runs at 100MHz instead of 10MHz (the Ethernet standard). It is very important to configure the pairing of wires correctly to optimize the speed of transmission. A LAN also requires that the individual computers have a network aware operating system installed such as LANman in DOS or Novell clients for Netware. Some versions of Windows, such as Windows 3.11 are network aware, while Windows 3.1 and earlier are not. Windows 95 is the best choice as it has the basic elements needed for TCP/IP networking built-in. An entry level peer-to-peer network is relatively inexpensive and simple to set up using Windows 95 PC's with NIC's and 10baseT cabling.
Back to Top

- M -

1 million bytes, a medium size PC has about 16MB of RAM.
Storage for data and processes in a computer. The contents of memory usually disappear when the machine is turned off. The usual name for this kind of memory is RAM. Some memory is designed to stay active either because it has a battery to keep it alive CMOS, or because it has a special Non-Volatile circuit, NVRAM.
1 million bits per second. A measure of digital communication speed.
'MegaHertz' or megacycles. If a PC has a speed of 100MHz that means that it will process 100 million machine cycles every second. If a particular computer uses 10 machine cycles on average for every instruction, then that machine would perform about 10 million instructions such as addition or data transfers every second.
Computer with a microprocessor CPU or CPU's.
Single IC containing all or most of a CPU.
Microsoft Corporation
Company started by Bill Gates and Paul Allen to market their 8-bit version of the BASIC programming language suitable for microcomputers. Later Microsoft developed a microcomputer operating system for small systems with floppy disk drives called MS-DOS. Today, of course, Bill Gates is the wealthiest geek on the planet, particularly with the spectacular success of Windows operating systems and various office and networking software products.
Microsoft joke
As told by Richard Spillman himself: "What is Windows 95? It's a 32-bit enhancement of a 16-bit upgrade of an 8-bit product for what was originally designed to be 4-bit processors and sold by a 2-bit company that doesn't care 1-bit for the competition."
A term from the early 1970's referring to computers making more use of integrated circuits instead of discrete transistors. An example is the Digital PDP-11 family. These machines were much smaller than machines they replaced, the 'mainframes.' A PDP-11/32 fit in a space the size of a file cabinet and may have had 5 MB of disk space and 4 KB of RAM but was considered a breakthrough at the time.
MOdulate-DEModulate device that converts a digital signal within a computer to an analog signal going out over the phone line and vice-versa.
A multitasking computer is capable of keeping several processes active at once. A computer with only one processor does multitasking by dividing up tasks and interleaving them in a single queue through that one processor. Windows 95 and Windows NT are multitasking operating systems. For a computer to serve several users at once it must have multitasking.
A multiprocessing computer has more than one processor. A multiprocessing system can split up a process and run parts of that task on separate CPU's to increase throughput, or it can run multiple processes splitting each task as before between processors, or it can assign different tasks to different processors outright. Multiprocessing demands a sophisticated operating system to keep track of process scheduling. The PCLES data server is a multiprocessing multitasking system running Sun Microsystems Solaris operating system. Windows NT is another operating system that can support multiprocessing.
A computer or a computer program which can handle requests or input from more than one user at a time. Such a computer must have either a multitasking or multiprocessing (or combination of both) operating system.
Microsoft Disk Operating System software. MS-DOS is the first software loaded on older PC's. MS-DOS is also known generally and incorrectly as DOS. In fact there are other DOS's such as UNIX and MAC-OS. MS-DOS was invented to support floppy disk based PC's although now it is usually installed on a hard disk and will communicate with CD-ROMS, tapes, etc. as well. The original versions of Windows (up to and including version 3) required that MS-DOS be loaded on the system. Windows 95, however, does NOT run 'on top of' MS-DOS and only simulates MS-DOS in order to support older software. MS-DOS is considered obsolete for most applications.
Back to Top

- N -

A networking product of Novell Corporation. Netware runs on top of an MS-DOS system to provide file service for a network. Netware's native communication protocol is IPX/SPX. It is possible to run TCP/IP with the appropriate module. Netware is not a complete operating system in the sense that UNIX or NT are. Running Netware on a computer makes that computer unavailable for local login so start it up and stick it in the closet.
A group of computers which communicate to share programs or data. Communication is usually done by hardwired digital connections over a LAN or WAN system. Although it is possible to connect computers with analog serial wiring, such an arrangement is too slow and unreliable to be useful for serious network
network card
network interface card
A pc board that when installed in a computer provides a network jack at the back of the computer.
A Network Interface Card.
NanoSecond: a time interval equal to 0.000000001 seconds. Grace Harper, one of the original computer gurus, used to carry around a little wire about a foot long: "This is a nanosecond," she would say holding up the wire. Then she would remind you that electrical signals travel at the speed of light at 186,000 miles per second, which is pretty fast, but even at that speed a signal only goes 11.8 inches in a nanosecond!
Windows NT.
Non-Volitile RAM, keeps its data even when power is removed. Some digital cameras have NVRAM modules on which images can be stored. NVRAM maintains the setup configuration on some computers while they are turned off although this function is usually performed with CMOS on microcomputers..
Back to Top

- O -

office suite
A collection of programs to perform common office or business functions. Microsoft Office, for example, contains a word-processing program (MS Word), a spreadsheet program (MS Excel), a program for creating graphical presentations such as slideshows (MS Powerpoint), and a database program (MS Access). Corel has a similar office suite.
operating system
Software such as MS-DOS, Windows 95, Windows NT, Solaris, UNIX, VMS, which control the basic operation of a computer to allow users to log in and run application programs.
Back to Top

- P -

Parallel mode of communication.. PC's usually have a 'parallel port' which is used to connect (one way) to a parallel printer. Other devices such as tape drives or external CD-ROM drives can use (two way) ECP ports which are enhanced parallel ports on newer PC's. Parallel ports communicate with a hardware handshake that tells the external device that the data on its pins are ready to be read all at once (rather than in sequence). A parallel port needs a separate pin for each bit of data that will be transmitted or received whereas a serial port needs a single pin for transmit and another for receive. You can easily identify the parallel port on a PC as it will have a socket for 25 pins to plug into. This connector is called a DCE-25 and if connecting to a printer will need a cable with a 'Centronics' connector on the end going to the printer. On an MS-DOS or Windows PC the first parallel port will be called LPT1: because it is assumed to connect to a 'Line PrinTer.' See serial.
A Printed Circuit. An electronic 'card' or 'board' made of insulated layer(s) of phenolic, plastic, or fibreglas supporting 'printed' wiring patterns. Pc boards are easily mass-produced by automated equipment. The circuit patterns are reproduced by photo-etch or photo-deposition processes leaving copper or aluminum conductive lines. Semiconductor and other electronic parts are attached by insertion into holes drilled or punched in the boards and then dipped into 'waves' of molton solder. The best high speed digital pcboards are produced in multiple layers with surface-mounted electronic components including IC's that need no mounting holes. Note the difference between pc and IC.
Personal Computer. IBM wants us to think it invented the name when it called its Intel 8085-based computer the IBM-PC in the late 70's. However there was already a growing market of PC's based on the earler Intel 8080 processor and Zilog's Z80 processor. The IBM-PC introduced MS-DOS to the small computer world and was instrumental in helping Microsoft achieve its early success. Older PC's used the then popular and now obsolete CP/M operating system produced by Digital Research. Note the difference between PC and pc.


A peer-to-peer network links individual PC's into a workgroup without authenticating passwords through a central server. Although such a system can be passworded, the level of security is minimal. Windows 3.11 and Windows 95 computers can be connected in a peer-to-peer configuration. As opposed to a client-server network..
Intel Corporation microprocessor chip, the successor to the 80486 CPU.
A program running in the computer is called a process.
A list of instructions for the computer either in source listing (human readable) or compiled form (machine readable). A program running in a computer is called a process.
A set of rules that define and control computer behavior especially for communication between computers. TCP/IP is the low-level protocol used on the PCLES system and by computers on the Internet. IPX/SPX is the name of the protocol used in many LAN's. Higher level protocols include http and ftp.
Back to Top

- Q -

A sequence of programs waiting to be loaded into a computer or a sequence of processes waiting for attention by the CPU.
Back to Top

- R -

Random Access Memory, memory which is only active while the system is powered up. Static RAM retains its data as long as power is applied, dynamic RAM also needs to be refreshed by a system signal. Memory speed is rated by the time needed to access data on the RAM chip, a medium speed PC these days has RAM with 70ns access time or less.
Network Reverse Address Resolution Protocol. Used to convert between Ethernet layer and IP layer data encapsulation. See ARP.
A network connection box, similar in appearance to a hub, that 'routes' or redirects traffic to specific ports to increase communication speed. Routers are used as 'bridges' between networks, to filter traffic for security, and to translate between different networking standards or protocols.
Back to Top

- S -

A material suitable for making electronic devices such as transistors, etc. The location of electrons in the outer levels of semiconductor atoms give these materials peculiar chemical properties. Junctions of these materials have electronic properties. Semiconductor materials include silicon, germanium, and gallenium.
Sequential mode of communication.. PC's usually have a couple of 'serial ports' which are used to connect a mouse or external modem, or, rarely now, a serial printer. Typical serial communication uses a sequence of ASCII codes for each of the characters to be transmitted. These codes are transmitted one bit at a time with appropriate 'start' and 'stop' bits. This common serial interface is an IEEE protocol known as RS-232C. Teletype, fax, and digital telephone are other examples of serial communication. On an MS-DOS or Windows PC the first serial port will be called COM1: and will have a connector with 9 protruding pins, this connector is called an RS-232C/DTE-9. The second port, COM2: usually has 25-pins, this connector is called an RS-232C/DTE-25. (at the PC, COM pins point out, LPT pins point in.) See parallel.
A computer, usually with some horsepower, that provides services...or... the software that runs on a such a computer to provide a particular service. The PCLES Web runs on a 'server' computer named PASCAL. The PCLES Web runs on an operating system called NT Server. The PCLES Web is a service provided by a module within NT called the Web Server (more correctly Microsoft IIS 3.0 or Internet Information Server version 3). Servers usually run all the time and provide services to users who log in over a network. A file server is a common type of server module that provides access to programs and data files and controls network communication. Other types of server modules provide electronic mail, remote access to dial-up users, database access, access to large applications, control of software licenses, etc., etc.
Programs, usually in their machine-readable form, that are executed on a computer. Software is usually obtained on floppy disk or CD-ROM disk. Once obtained, software must be 'installed' on the system usually following on-screen instructions in which the user answers questions about options desired for its operation. New computers often have operating system software pre-installed for the convenience of inexperienced users.
Program which simplifies calculations arranged in a table of rows and columns. Spreadsheet programs such as Microsoft Excel, Corel Quattro, or Lotus 123 are extremely useful for creating budgets, financial projections, invoicing, etc., etc. It is much quicker and easier to perform calculations in a spreadsheet than to write a special program. Moreover once the details of a calculation are worked out the table can be saved as a computer file to be reused or modified later. Tables created in spreadsheet programs can be easily copied into wordprocessing documents in most cases. 'See office suite.
Back to Top

- T -

The most widely used digital communication protocol. TCP/IP is the language spoken on the Internet and on the PCLES Web. Transmission Control Protocol/Internet Protocol was first used on UNIX systems in the 80's and now is the basis for much of the most sophisticated communication. The Internet is based on and gets it name from TCP/IP.
A device with a monitor and keyboard designed to communicate over the network with a server. Although a terminal may resemble a PC it does not have a local CPU accessible to the user. Usually the giveaway is the absence of a box containing disk drives, etc. Unlike a PC a terminal cannot perform tasks without being connected to the network. Unlike PC's terminals cannot communicate directly with each other, all terminal communication goes through the central computer. Since they use serial communication lines terminals cannot be connected directly into a 10baseT hub even though they may have the same kind of connector, instead they connect to a terminal server which translates the serial data into TCP/IP.
terminal server
Network device that translates network protocols such as TCP/IP to serial data suitable for terminals. Routers often have terminal server modes or can be reprogrammed for this function.
Electronic device formed by the junction of three layers of semiconductor material. Current through the 'bread' of such a sandwich is controlled by a much smaller signal applied between one slice and the thin filling between them. A transistor junction can be size of a dime to carry a heavy current or microscopic. Typically microcomputer chips have millions of transistors etched on them.
Back to Top

- U -

Copy data from a 'little stupid' computer to a 'big smart' computer, a client to a server, a workstation to a host, a dedicated microcontroller to host computer, or a local computer to a remote computer. Opposite of download.
An operating system invented at Bell Labs in the 60's. At the time a huge system called MULTICS was being developed. The guys who started UNIX wanted a simpler multiuser system that could run on a variety of hardware platforms. They were very successful in their design and UNIX has been the operating system of choice for multiuser systems worldwide. UNIX has not been able to scale down easily to a graphical desktop PC and so now is being overtaken by operating systems such as Microsoft Windows. The PCLES database system, Spillman Data, runs on a Sun Microsystems computer with an operating system called Solaris. Solaris is modern version of UNIX which is very successful especially as an internet engine. Sophisticated UNIX systems have graphical windowing systems, the most common of which is X-Windows.
Back to Top

- V -

virtual machine
Some computer servers create a customized work environment when the user logs in. That user always sees everything on the 'desktop' just as it was left on the previous session. If other users are logged in on the same machine, as over the network, they do not see each other. When a user logs off such a machine, any programs started on that VM are shut down. A UNIX computer such as the PCLES Sun data server does NOT use virtual machine sessions for login normally. If a user process needs to stay running after logoff on a VM computer such as Microsoft Windows NT Server, that process needs to be 'virtualized' or 'daemonized' meaning that it is runs outside of the VM control.
Back to Top

- W -

Wide Area Network. An extended network with point-to-point links such as leased lines. A WAN may extend over serveral sites within a city or may spread over sites in different countries. As opposed to a LAN...
web page
Data written in hypertext (HTML) which can be viewed on a local network or on the Internet using web browser software.
The World Wide Web, an Internet form of communications through web pages.
Operating system that presents to the computer user multiple graphical views of executing programs. Microsoft Windows is such a class of products although versions prior to Windows 95 were not true operating systems and would not run without the presence of MS-DOS.
Windows 95
Version of Microsoft Windows first released in August 1995. Windows 95's networking capability is much improved over earlier Windows versions. Many basic networking protocols are built-in.
Windows NT
Microsoft Windows New Technology operating system available in two versions: NT Server and NT Workstation. Both are multitasking systems with an appearance similar to Windows 95. NT Server provides some system services not available in NT Workstation and is much more expensive. Otherwise they are virtually the same. NT's filesystem (called NT Filesystem) greatly improves security over MS-DOS and earlier Windows systems (FAT filesystem).
Back to Top

- X -

A windowing system used on some UNIX computers. Usually not refered to as 'X-Windows' but simply as 'X'.
Back to Top

- Y -

A system in UNIX that is used to write more systems in UNIX. Stands for Yet Another Compiler Compiler.
Back to Top

- Z -

A fast and efficient protocol for downloading information by modem from computer bulletin boards. In Windows 95 systems, zmodem software is built into the Hyperterminal program. Of several common protocols such as Kermit, xmodem, etc., Zmodem is the most versatile.
Back to Top

- # -

10 megabit per second, 'thin' coaxial cable Ethernet LAN wiring scheme. 10base2 is wired in a daisy chain pattern using tees and BNC connectors. Both ends of a 10base2 backbone must be terminated with the appropriate resistor. Generally more expensive and less reliable than 10baseT.
10 megabit per second, 'fat' coaxial cable Ethernet LAN wiring scheme. 10base5 is wired in a daisy chain pattern using tee adapters with DTE-15 AUI connectors. 10base5 is the original Ethernet configuration but is considered obsolete now for most applications.
Ethernet LAN wiring scheme using optical fibre cabling.
10 megabit per second, twisted-pair Ethernet LAN wiring scheme. 10baseT is wired in a star pattern with each leg of the network connected to a local hub. Many networks now use 100baseT wiring to increase the speed. The speed is determined by network cards in the computers as well as by the characteristics of hubs, routers, and cabling in the network.
100Mbs version of 10baseT. Requires use of Cat 5 cabling.
386 Computer
A computer having an Intel 80386 microprocessor. Arguably the first 'serious' PC chip in that it was designed to handle the various addressing modes and data width necessary for multitasking applications. Early '386's were made in speeds of 16 or 20 MHz by Intel. Advanced Micro Devices (AMD) made news by introducing a 40MHz '386. Intel sued AMD for copyright violation and lost. AMD showed that its chip performed exactly the same as Intel's but internally had a different design. In an attempt to gain more market share Intel offered a cheaper brain-dead version of the '386 called the '386SX. The SX version had a narrower data path and turned out to have early obsolence compared to the standard '386DX. The '386 and earlier x86 chips needed a coprocessor to handle decimal or 'floating point' calculations. This chip is the 80387. Although 386 computers are mostly obsolete now a computer with 8MB of RAM, a '386DX-40 CPU, and a '387 coprocessor installed will run Windows 95... slowly.
486 Computer
A computer having an Intel 80486 microprocessor. The '486 has multi-thread capability so it can better handle multitasking operations.
A byte, a code having 8 on/off states or bits which means it can have 256 possible values. The first PC's were said to be 8-bit because the largest integer number value they could handle at a time was 255. Numbers larger than that were calculated by concatenating these values together. Newer PC's such as Pentium's can handle 32-bit calculations, i.e. for integers up to about 4 billion in a single instruction. High-end PC's such as Sun Microsystems' Ultra and Digital's Alpha can handle 64-bit calculations.
Back to Top
Revised: April 24, 2001.
Copyright 1997 by PCLES Regional System