a semi-precise and
somewhat biased explanation of some computer terms...
- 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.
...as 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
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
- 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.
- 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 'http://www.microsoft.com/' (look for
MSIE download area). Some tips for using your browser on
PCLES Web can be found at PCLES Web
- '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.
- 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
- 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,
- Starting with AT
compatible PC's, setup configuration was stored on a
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
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
language that translates human-readable source code
into machine code using the instructions of a
- A device capable of automatically executing programs. Computers are
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
- 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.
- 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.'
- 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.
- '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
- 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.
- 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
- (usually pronounced gig-a-bite, not jig-a-bite) 1 billion
bytes, typical size of
medium sized PC hard disk.
- 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
- <!DOCTYPE HTML PUBLIC
content="Microsoft FrontPage 2.0">
content="Microsoft FrontPage 2.0">
somewhat biased explanation of some computer terms...</font></h1>
<h1><a href="buzzwords.htm#sectA"><font color="#408080"
- href="buzzwords.htm#sectY"><font color="#408080"
color="#408080" size="5"><strong> </strong></font><a>
color="#408080" size="5"><strong> </strong></font><a>
<h1><a name="sectA">- A -</a></h1>
<dd>The <a href="#Digital
Equipment Corp">DEC</a> Alpha is
the world's fastest
<a href="#chip">chip</a>. Alpha <a href="#CPU">CPU</a>'s
are 64 bit RISC
chips available in speeds up to 500<a
<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
- 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
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
- Words in a document such as a web page which contain
links to other documents or resources. See HTML.
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
- 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'
- 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
- 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.
- kilo-bits-per-second, a measure of transmission speed in
communication circuit. A medium speed computer modem would have a
transmission speed of 28.8kbs. The fastest modems have
double this speed.
- 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.
- 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
- 1 million bits per
second. A measure of digital
- '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.
- 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
- 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
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
- 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.
- 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
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
- A NIC.
- A pc board that when installed in a computer provides a
network jack at the back of the computer.
- A Network
- 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..
- 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.
- 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
- Intel Corporation microprocessor chip, the successor to the
- A program running in
the computer is called a process.
- A CPU.
- 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
- A sequence of programs
waiting to be loaded into a computer or a sequence
of processes waiting
for attention by the CPU.
- 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
- 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
- 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
- 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
- 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
- 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.
- 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.
- 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.
- 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
- A windowing system used on some UNIX computers. Usually not
refered to as 'X-Windows' but simply as 'X'.
- A system in UNIX that is
used to write more systems in UNIX. Stands for Yet
- A fast and efficient protocol
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.
- 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
- 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
- 100Mbs version of
10baseT. Requires use of Cat
- 386 Computer
- A computer having an Intel
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
- 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.
Revised: April 24, 2001.
Copyright © 1997 by PCLES Regional System