ACK - ACKnowledge. [Ack] A transmission control character that is a response to the sender acknowledging correct receipt of a block of data.

ADSL Asymmetric Digital Subscriber Line (or Loop). One of several techniques for delivering higher speed data to end users through the existing telephone or cable networks. In ADSL the speed in the downstream direction is much higher than that in the upstream direction.

ANSI - American National Standards Institute. [An' Sea] A volunteer organization that helps industry set standards and represents the United States in the ISO.

ANSI.SYS - [An' Sea Dot Sys'] A device driver loaded by the CONFIG.SYS file under DOS, Windows 3.x or Windows ’95 that provides control over the screen in a manner similar to that used for certain dumb terminals.

API - Application Program Interface (or many slight variants of). Many systems provide specifications and software libraries so that users can write programs that use components of a system to create different applications. For example, a system that was designed to access a scanner with a vendor supplied program might provide an API for users who need to add scanner capabilities to an application.

APPC - Advanced Program-to-Program (or Peer-to-Peer) Communication. A special API that provides that ability for a program operating in one IBM environment to exchange information interactively with a different program in another environment. Especially IBM's Logical Unit (LU) 6.2 specification.

ARCNET - Attached Resource Computer NETwork. [Arc' Net] One of the earliest LAN's, developed by Datapoint Corp. Still functional and supported by most OS’s, but having virtually no future growth path.

ARP - Address Resolution Protocol. [Arp] A part of the TCP/IP process of mapping IP addresses to network hardware (MAC) addresses.

ARPA - Advanced Research Projects Agency. [Are Puh] Part of the Department of Defense that funds much computer research, and in particular installed the first packet switched network and the huge research called the Internet.

ASCII - American Standard Code for Information Interchange. [Ass' Key] This standard defines a seven bit character set that is intended for communication among computers. The IBM PC line uses an eight bit character set which is a superset of ASCII.

ASIC - Application Specific Integrated Circuit. [A' sic] An integrated circuit created for a limited application by modifying a standard generic mask. They help make PC's cheaper and more reliable.

AT (PC/AT) - The third major type of personal computer sold by IBM. It used an 80286 CPU chip and had a 16 bit data bus.

ATM – Asynchronous Transfer Mode. A physical layer transmission protocol designed to allow multiple types of communication with different characteristics simultaneously across a single link. (E.g., it allows data, voice and video all at the same time.)

BALUN - BALanced/UNbalanced. [Bay' lun] or [Bal' un] An impedance matching device that converts unbalanced transmission systems (i.e., Coax or Twinax) to balanced transmission systems (i.e., twisted pair) and vice versa.

.BAT - BATch file extension. [Dot Bat] A PC file containing commands that DOS will execute when it is asked to run the file.

BCC - Block Check Character. A generic term for redundancy checking characters such as CRC and LRC.

BIOS - Basic Input Output System. [By' oss] The lowest level layers of computer operating system software, usually having to do with direct control of the hardware. Almost always stored in ROM's on the motherboard. Some controllers contain BIOS extensions.

BISYNC - BInary SYNChronous. [by' sink] An IBM specification for communication between certain computers and terminals. Still in use for older devices but not for new products.

BIT - BInary digiT. [Bit] The smallest unit of information, it has only two values. These two values can represent Yes or No, True or False, 0 or 1, or whatever the users agree on. It is the basis for all digital computers.

BNC - Bayonet-Neill-Concelman. A type of connector for thin coax cables. It locks into position with a push and a 1/4 turn. There is some argument about the origin of this acronym, but this one is generally accepted. The significance is always the same.

BOB - Break Out Box. [Bob] A tool (small box) that can be inserted between two connectors and "breaks out" the individual signal wires so that they can be monitored, opened, patched, and measured. Used as a diagnostic tool to solve interfacing problems. Most often seen in RS232 serial devices.

BPS - bits per second. A speed rating for serial devices, and in particular for modems. Common PC rates are 300 to 56,000 bps. (Use this term in preference to the more technical term "baud" which does not mean the same thing as BPS.)

BS - BackSpace. A transmission character that moves the active position (usually the cursor) back one space to the left.

BSC - BiSynChronous. See BISYNC.

CAD - Computer Aided Design. [Cad] or [C A D] Computer software (and sometimes hardware) for automating the task of designing hardware things. May be fairly simple or may include many task oriented features such as printed circuit layout, rotation of solid objects, automatically removing hidden lines, etc.

CAM - Computer Assisted Manufacturing. [Cam] Systems that assist in the manufacturing of goods. May be rather simple systems such as Bill of Materials Processing (BOMP) all the way to fully automated robotics systems. Often combined with CAD as in CAD/CAM.

CCITT - Comite Consulatif International de Telegraphie et Telephonie. An international group that sets communication standards. Many of these standards have names like V.21, V.335, X.25, and V.32 bis. (This is one of those groups that changes its name every few years.)

CD - Carrier Detect. One of the signals in an RS-232 interface. Indicates that the DCE device (modem) has detected a carrier on the line, i.e., it is talking to the modem at the other end. Sometimes this term is used as an abbreviation for CD-ROM. You should not usually have trouble telling which is meant by the context.

CD-ROM - Compact Disc - Read Only Memory. [Sea dee rawm] Just like your home CD player but containing data intended for computer access.

CGA - Color Graphics Adapter. A video controller that supports four color graphics but has very poor resolution in text modes. Obsolete. Never good for anything but toys.

.CGM - Computer Graphics Metafiles file extension. One of many formats for storing graphics oriented data. Not much used any more.

CISC - Complex Instruction Set Computer. See RISC, of which this is the opposite. The Intel x86 family which is used in the IBM PC is normally considered to be a CISC machine.

CLEC – Competitive Local Exchange Carrier. Some business other than your local phone company who can provide you with normal phone service.

CMOS - Complimentary Metal Oxide Semiconductor. [Sea' moss] A type of integrated circuit device. The chief virtue of these devices is that they use very little power. They are thus often used for portable, battery operated devices. CMOS ROM's are used in AT and larger machines to store the BIOS setup information.

CPU - Central Processing Unit. The part of a computer that performs logical and arithmetic operations. This term is very relative. The exact meaning depends on your point of view.

.COM - COMmand file extension. [Dot Cawm] These files can be loaded by DOS to perform a "Command". The distinction between .EXE and .COM files is not meaningful for users.

CP/M - Control Program for Microcomputers. A PC operating system from Digital Research that preceded DOS. Now obsolete. See DR-DOS.

CRC - Cyclic Redundancy Check. A mechanism for insuring the integrity of a block of data (especially during transmission or storage) by computing an arithmetic function from the data and writing it with the data. Upon receiving the block, the receiver recomputes the function. If the values match, then the block is most likely correct. A CRC operates on multiple bytes in each step in the computation. A similar method is a Longitudinal Redundancy Check, or LRC, which operates on only one byte in each step. The CRC is more complex, but more reliable.

CSMA/CD - Carrier Sense Multiple Access/ Collision Detection. A LAN protocol in which any device is free to transmit at any time no other device is transmitting. It detects errors caused by having another device beginning to transmit at the same time. It is used by Ethernet LAN's which are not running in Full Duplex mode.

CSU - Channel Service Unit. A device used in connecting a computing device to a digital circuit such as a DDS or T1 line. Also needs a DSU. Usually these are combined into one unit called a CSU/DSU. This is so common that a combined CSU/DSU is often called a CSU.

CTS - Clear To Send. One of the signals in an RS-232 interface. Indicates that the DCE (modem) side is ready to accept data from the terminal and transmit it on the line to the receiver.

DAT - Digital Audio Tape. [Dat] The latest development in audio tape technology, this device is also available for backup of computer data.

DBMS - Data Base Management System. A collection of programs that facilitate storage and retrieval of large amounts of similar, highly structured data. (You can get into a lot of arguments about precisely what does and what does not constitute a DBMS. Many people have very specific meanings when they use the term. Others are more vague.)

DCE - Data Communication Equipment. In many interfaces, one side must take one role and the other side must take a complimentary role. DCE is one role, specifically with respect to the RS-232 interface and its kindred. It refers to the modem if there is one involved. The opposite side is the DTE. It is possible to connect two devices that normally would each think they were a DCE using a "null modem" or Crossover Cable. Each device will think of itself as the DCE.

DD - Double Density. Personal Computers prior to the IBM PC generation had floppy drives that were even lower density (DS/SD) than the 360K floppy. They were sometimes written on only one side (SS/SD). The PC used a drive that was double the previous density. Usually written as DS/DD.

DDS - Dataphone Digital Service. A type of communications line provided by the phone companies that is digital rather than analog as is a normal telephone circuit. These were normally permanently connected leased lines rather than dial access circuits. See also DSL and ISDN.

DECNet - Digital Equipment Corporation NETwork. [Deck' net] A proprietary network architecture that works on all DEC machines. Includes a peer to peer interface.

DES - Data Encryption Standard. [Dess] A scheme approved by the National Bureau of Standards and by FIPS PUB 46 for encrypting and decrypting data for security purposes, especially for transmission purposes.

.DHP - ??? file extension. One of many formats for storing graphics oriented data.

DIP - Dual Inline Package. [Dip] The shape of a small integrated circuit package that has two rows of pins. It resembles somewhat a flat caterpillar. Switches used for configuring older PC boards often are in DIP form, and hence are called DIP switches.

DLC - Data Link Control. A networking protocol layer that defines the mechanisms, both physical and logical, for establishing a link between two stations on a network. It is above the physical layer and below the network layer in the OSI model.

.DLL – Dynamic Link ????? Library. These files are system routines that are needed by Windows applications often but not always. They are loaded when needed rather than being made a part of the resident operating system. This way they take up less RAM. They can be shared by many programs, however, so each program does not have to have the code built into it. This makes the programs slower to start up but faster to run.

DMA - Direct Memory Access. A type of computer interface circuit that allows a peripheral device to access the main memory of a computer without any help from the CPU. DMA devices help the system run faster.

DNA - Digital Network Architecture. A DEC data communication protocol.

DNIC - Data Network Identification Code. [???] A 4 digit number assigned to PUBLIC data networks and to specific services therein.

DOS - Disk Operating System. [Doss] In the PC world this refers to either PC-DOS, MS-DOS, or DR-DOS. Otherwise it is a generic term, having been used previously to name similar systems on mini and mainframe computers.

DR-DOS - Digital Research - Disk Operating System. [De are Doss] or sometimes [Doctor Doss] A DOS created by DR to be compatible with MS-DOS and PC-DOS, only better.

DS - Double Sided. The original IBM PC had a floppy drive that only used one side of the disk.

DSR - Data Set Ready. One of the signals in an RS-232 interface. It means that the DCE (modem or data set) is ready to initiate communication with the DTE (terminal or computer).

DTE - Data Terminal Equipment. The compliment of the DCE in an RS-232 interface.

DTR - Data Terminal Ready. One of the signals in an RS-232 interface. It means that the DTE device is ready to initiate communications.

.DXF - ??? file extension. One of many formats for storing graphics oriented data.

EBCDIC - Extended Binary Coded Decimal Interchange (or Interface) Code. [Ib' sea dick] An 8 bit character set defined by IBM. It is used in their mini- and mainframe computers, but not in their PC's. (PC's can communicate in EBCDIC by converting data as it is sent or received). See also ASCII.

EDO RAM – Extended Data Output. ?????

EEROM - Electrically Erasable Read Only Memory. [Ee' Ee' rom] or [Ee' squared rom] Integrated circuit memory that a system can write into but that will retain its contents when the power is turned off. Usually used for storing setup or configuration information. See EROM or EPROM. Sometimes called Flash ROM or Flash PROM.

EGA - Enhanced Graphics Adapter. A color graphics video controller. It better than CGA but not as fine as VGA or SVGA. Now effectively obsolete.

EIA - Electronics Industries Association. A voluntary standards organization. It is a contributor to the ANSI.

EISA - Extended Industry Standard Architecture. [Ee sah] A PC bus design used by other vendors to compete with IBM's MCA bus. While this bus allows the use of 32 bit data path boards, it is also compatible with older ISA cards, unlike the MCA bus. Now obsolete.

ELS - Entry Level System. Versions of Novell 286 NetWare, ELS I and ELS II were the low end products prior to release 2.2. These versions are no longer sold. They supported limited numbers of terminals and required significantly less installation work but had fewer options than larger versions.

EMI - ElectroMagnetic Interference. Interference between devices that is conveyed by magnetic coupling rather than by radio waves. (See RFI.)

.EPS - Encapsulated PostScript file extension. One of many graphics data file formats. PostScript is a printer control language defined by Adobe Systems, output by many graphics systems, and processed directly by many printers.

EROM (or EPROM) - Erasable [Programmable] Read Only Memory. [Ee' rom or Ee' prom] An integrated circuit device that was normally intended to store data that changed only very rarely or never. The device could be erased, usually with ultraviolet light, and then rewritten. Most often used for programs like the BIOS. Flash PROMS are a variant that can be rewritten electronically under program control without the UV light erasure step.

ESDI - Enhanced Small Disk Interface. [Ez' dee] A class of PC disk controllers. Now obsolete.

.EXE - EXEcutable program file extension. A file extension marking one of the two types of files on a PC that DOS can load into memory and run. Windows has many other extensions for such executable programs.

FDDI - Fiber Distributed Data Interface. This is an ANSI standard for a 100 Mbps LAN. It was originally designed for fiber optics connections, but is now being implemented with copper wire technology. It is a Token Ring topology. It is fast but very expensive.

FDM - Frequency Division Multiplexing. Simultaneously sending several signals over one medium by sending them at different frequencies much like a cable TV does. (See TDM.)

FDX - Full DupleX. Transmission that can take place in both directions at one time. Note that the medium can be FDX and be used only in HDX mode. (See HDX.)

FIPS PUB - Federal Information Processing Standards PUBlication. [Fips Pub] Publications that define data processing standards for government agencies. These are not industry standards, but often become de facto standards because the federal government is such a large purchaser.

FLOPS - FLoating point Operations Per Second. [Flops] A measure of the speed of a computer system when executing mathematically oriented operations. Usually given in MegaFLOPS. (See prefix M.)

FSK - Frequency Shift Keying. A method used by low speed modems to put a data signal over an analog phone line.

G - Giga-. A prefix indicating 1 billion. [Sometimes said a Gig.]

.GEM - ??? file extension. [Gem] One of many formats for storing graphics oriented data.

GUI - Graphic User Interface. [Gooey] This term refers to a style of man/machine interface used by Windows. It involves using a mouse to move a pointer on the screen and pointing to little pictures (or Icons) that symbolize the intended operation. For example a wastebasket might symbolize a delete operation.

HD - High Density. Said of floppy drives or drives, as contrasted with Double Density (DD).

HDLC - High-level Data Link Control. An international standard data communication protocol. Similar to IBM's SDCL.

HDX - Half DupleX. Transmission that takes place in only one direction at a time. (See FDX.) Human conversations are normally half duplex unless people are really excited.

HLL - High-Level Language. A programming language in which the basic operations are related to the solution of the problem rather than to the direct operation of the computer.

HGA - Hercules Graphics Adapter. A video controller that allows graphics images on a monochrome video. An older device than the MCGA, it uses shades of gray to simulate different "colors". The software sometimes can be configured to think that this controller is a CGA controller. Now virtually obsolete.

HPGL - Hewlett-Packard Graphics Language. One of many formats for storing graphics oriented data. Originally designed to control the HP LaserJet printers.

HPLJ[II or III] - HP Laser Jet [II or III]. Laser printers from Hewlett-Packard. These printers are frequently emulated by other laser printers.

HPPCL - Hewlett-Packard Printer Control Language. The ESCape sequence commands that are used to enable advanced printing functions on a HP LaserJet printer. This syntax is often emulated and even used for graphics file formats.

HTML – HyperText Markup Language. A specification for formatting a text document so that it retains a certain amount of formatting information and can readily be transported across a network and displayed on a variety of different platforms.

HTTP – HyperText Transport Protocol. A protocol used by web servers to request/send documents stored in HTML, q.v., and associated other objects. 9 e.g., images, sound clips, etc.)

Hz. - Hertz. [Hurts] (Not an acronym.) The same thing as cycles per second. I.E., 60 Hz power is 60 cycles per second. A 250 MHz PC executes 250 million instruction cycles per second.

IDE - Imbedded Drive Electronics - The newest and least expensive of the common PC hard disc interfaces. The controllers are very cheap but not the fastest. (See SCSI.)

IEEE - Institute of Electrical & Electronic Engineers. [Eye triple Ee'] A professional organization for electrical engineers that is active in setting standards, especially for LAN's. The IEEE 802.n standards all concern LANs.

.IMG - Image file extension. One of many formats for storing graphics oriented data, used by GEM Paint.

I/O - Input/Output.

IPX - Internet Packet eXchange. The lowest layer of protocol in a Novell network. For many years this has been the standard, but Novel is now yielding to TCP/IP, mostly because of its success in the Internet.

IRQ - Interrupt ReQuest. A signal in a PC that a peripheral device uses to tell the CPU that it has data ready to be transferred. Most PCs have 16 (numbered 0-15).

ISA - Industry Standard Architecture. [Eye' sah] This term is used by other vendors to generically describe the IBM AT bus. This bus is capable of using cards designed for the IBM AT with a 16 bit data path or those designed for the PC and XT with an 8 bit data path. This bus is also used in the lower models of the IBM PS/2. See also EISA, MCA PCI and USB.

ISO - International Standards Organization. [ Eye' So] An organization that is the counterpart of the ANSI on an international level.

JDBC – Java DataBase Connectivity. A standard (API) that allows Java programs to interface with database services in a generic manner so that the programs do not have to be rewritten to move the database to a different service.

JCL - Job Control Language. Command syntax used to control batch job execution. Originally referred to IBM 360 operating systems, but now used more loosely by many vendors for similar languages on PC's.

ISDN - Integrated Services Digital Network. A special class of circuit from the phone company designed to carry digital information rather than analog voice signals only. It allowed both voice and data calls to take place at the same time over the same wire pair.

K - Kilo-. Generally a prefix indicating times 1000. In the computer world, this is almost always used to mean 1024. This odd usage comes about because of the internal workings of the hardware. Ten bits of data can exactly represent 1024, and for most purposes this is close enough. For example, 2 KBytes = 2048 bytes, not 2000.

LAM – LAN Access Module. A part of a concentrator (hub) in an IBM Token Ring network.

LAN - Local Area Network. [Lan] A mechanism for attaching several computers (especially PC's) together for the purposes of sharing programs, data files, and expensive peripheral devices and for facilitating work group cooperation and communication.

LCD - Liquid Crystal Display. A method for making display screens that are flat and very thin. They are commonly used in portable, laptop, and notebook computers.

LEC – Lan Emulation Client. A functional part of an edge device (bridge or router) in an ATM network that is running LAN Emulation (LANE).

LECS – Lan Emulation Configuration Server. A functional part of an ATM network that is running LAN Emulation (LANE).

LED - Light Emitting Diode. [Often El Ee Ded, occasionally Lead] Small lights made the same way transistors and integrated circuits are. They use low power and low voltage, so they are ideal for small machines used close up. Used as indicators to show power on and other binary status conditions.

LES/BUS – LAN Emulation Server/ Broadcast and Unknown Server. Two functional parts of an ATM network that is running LAN Emulation (LANE).

LIM[4.0] - Lotus Intel Microsoft. [Lim] A specification for the design and use of Expanded Memory hardware that can be added to AT class machines. This class of memory is not supported by all software packages. Now obsolete but still supported in Windows for legacy programs.

LLC - Logical Link Control. The second layer in the IEEE OSI LAN protocols. It defines a link that assures communication; i.e., it defines error correction procedures.

LRC - Longitudinal Redundancy Check. See CRC.

LSI - Large Scale Integration. Integrated circuits containing several thousand transistors or more in one chip. See VLSI.

LU 6.2 - Logical Unit 6.2. [El you six dot two] See APPC.

M - Mega-. A prefix indicating 1 million, but see K.

m - Mille-. A prefix indicating 1 thousandth. Unlike the integer prefixes, these fractional prefixes are used literally in the PC world. Thus a millisecond is really a thousandth of a second. The symbol for a millionth is the Greek letter mu, written rather like a script letter u with a tail. Things on hard disks happen in the 10 msec. range.

MAC - Media Access Control. [Mac] The lowest portion of the IEEE OSI LAN specifications that define the way that workstations will gain access to the medium in a LAN. Most often used in connection with a MAC address, the hardware address built into a network adapter.

MAP - Manufacturing Automation Protocol. [Map] A LAN protocol using a token bus process and broadband cables. Originated by General Motors among others. Not widely used outside this industry.

MAU - Multistation Access Unit. [M-ow (like how)] A wiring concentrator used to connect various devices in Ethernet or Token-Ring LANs.

MCA - Micro-Channel Adapter. A high performance bus designed by IBM for use in some PS/2 systems. It supports 32 bit data paths and has other advanced features but is not compatible with ISA (AT) bus cards. Now obsolete.

MCGA - MonoChrome Graphics Adapter. A PC video adapter with only one color but supporting graphic images as well as text. It is similar in function to a Hercules brand monochrome adapter that also does graphics, but is programmed differently. Rapidly disappearing because the cost savings are not sufficient. Everybody now watches color TV.

MDA - Monochrome Data Adapter. The simplest and cheapest type of PC video controller. It supports only one color and no graphics, only text. Still used for systems that are only used for status indicators and not used much for human interaction.

MEG - MEGaBytes. [Meg] Short for MegaBytes of data storage space, usually RAM, hard drives, or floppy disks.

MFM - Modified Frequency Modulation. The most common type of early PC hard disk controller and the method it uses to record the data on the disk. Commonly (but misleadingly) applied to the controller and the drive. Now obsolete.

MHS - Message Handling System - A component of Novell networks that lets EMail systems interface with the Novell EMail functions and services.

MIDDI - ???. [Mid' ee] A specification of an interface and devices intended for producing digitally controlled music. It exists independently of computers, but adapters and software for the PC are now fairly common.

MIPS - Million Instructions Per Second. [Mips] A rating of the overall speed of a computer's processing unit.

MNP(-5) - Microcom Network Protocol. A series of modem standards developed by Microcom Corp. The first five have been released to the public domain. The fifth deals with error correction. The MNP-7 specification deals with data compression. MNP-5 is a current de facto standard for medium speed modems.

MODEM - MODulator/dEModulator. [Mo' dim] A device that converts digital data to analog format for transmission over an analog medium, usually a phone line. It performs the inverse conversion when receiving data. It may also perform other related functions such as answering the phone, dialing the number, etc.

MOS - Metal Oxide Semiconductor. [Em Oh Ess, or sometimes Moss] A type of integrated circuit. Devices built with MOS circuitry used less space than devices built with prior technology (known as TTL or bipolar), and thus the devices could be made more complex (or much cheaper). The various common types of MOS are N(egative) MOS, P(ositive) MOS, and C(omplimentary) MOS. The latter is seldom encountered in modern machines except for laptops. It is the slowest of the three, but has the lowest current requirements. There are other proprietary variations.

MPOA Multi-Protocol Over ATM. A specification that allows layer 3 switching (i.e., routing) to take place in ATM networks.

.MSP - MicroSoft Paintbrush file extension. One of many formats for storing graphics oriented data.

MTBF - Mean Time Between Failure. How long can we expect a given device to run without breaking. (Mean = average.)

MTTR - Mean Time To Repair. When it does finally break, how long can we expect it to take to repair it.

MS/DOS - MicroSoft/Disk Operating System. [M S dos] A computer program created for control of 8086 (and later versions as well) based Personal Computers and licensed to hardware vendors for sale with their systems.

n - Nano-. A prefix indicating 1 billionth. PC RAM's cycle at about 70 nseconds, more or less. The static RAM chips used in the cache memory for machines usually cycles at about 10 ns.

NETBIOS - NETwork Basic Input Output System. [Net bi' aus] An IBM standard interface that allows certain PC operations to take place over a LAN. Many other network vendors provide an interface that is NETBIOS "compatible" because many software packages have been written around this specification. The word "compatible" is quoted here because there has been some difficulty with the various emulations of this specification.

NIC - Network Interface Card. [Nick] An adapter card in a PC that connects it with the LAN cabling system.

ODBC – Open DataBase Connectivity, A standard (API) that allows programs to interface with database services in a generic manner so that the programs do not have to be rewritten to move the database to a different service.

OH - Off Hook. The name of an RS-232 interface signal. It indicates that the modem has effected an "off hook" operation to answer a call or to prepare to dial.

OS/2 - Operating System/ 2. Derisively, [Oz two], Normally [Oh ess two] An operating system for IBM PC's, in particular designed to support the PS/2. It is a follow-on to PC-DOS and provides both multitasking and windows. IBM has announced that they are discontinuing development of OS/2.

OSI - Open Systems Interconnection. An ISO model that gives a framework around which to design LAN components. This specification divides the LAN interface into seven layers. Alternatives are TCP/IP and to a lesser extent, SNA.

p - Pico-. A prefix indicating 1 trillionth. Most PC's are not yet fast enough that anything of interest happens in the psec. range.

PAD - Packet Access Device or Packet Assembler/Disassembler. [Pad] Interface that allows a PC to connect to a packet switching network. (See X.25.)

PABX - Private Automated Branch Exchange. A computerized PBX.

PBX - Private Branch Exchange. A manual private telephone exchange.

PC - Personal Computer. In this context, specifically one of the original series made by IBM based on the 8088 CPU integrated circuit (IC) family; generically, any personal computer.

PC/DOS - Personal Computer/Disk Operating System. [Pea sea dos] IBM's proprietary version of MS/DOS.

PCI – Peripheral Component Interconnect. A PC bus with higher speed and greater width than the ISA, EISA and MCA buses that proceeded it. Currently the most popular standard for most high-speed devices.

PCL - Printer Control Language. Most often HPPCL.

PCM - 1) Plug Compatible Manufacturer. A manufacturer of a machine that emulates another (a common term in the mainframe market - in the PC world they are usually called "clones".)

.PCX - Not an acronym. A generic file extension used for several different formats for storing graphics oriented data.

PDN - Packet (or Public) Data Network. A data communications network that uses a protocol called X.25.

PGA - Professional Graphics Adapter. A high-end graphics adapter developed by IBM. It is not very common, having been largely replaced by the VGA and SVGA adapters.

.PIC - PICture file extension. One of many formats for storing graphics oriented data. This generic file extension is used by Lotus 123 (among others) for different file formats.

PNTG - ???. One of many formats for storing graphics oriented data.

POP – Point Of Presence. The nearest switching office of the telephone company.

POTS - Plain Old Telephone Service. The kind of analog service we have had in our homes for the last 40 years or so.

PROM - Programmable Read-Only Memory. Computer memory that can be programmed by the manufacturer who incorporates it in a device but is mostly read-only.

PPIC - ???. One of many formats for storing graphics oriented data.

PS/2 - IBM's latest class of personal computers. Unfortunately, the term was also applied by IBM to machines that are not substantially different from AT systems. The PS/2 models below the model 50 were similar to AT machines and the model 50 and higher were based on the 80386 processor (or higher) and incorporate the MCA bus.

RAID (0-5) - Redundant Array of Inexpensive Disks. Specifications that detail a variety of ways to hook several small disk drives together so that they appear as a single large disk and provide some extra measure of redundancy and reliability.

RAM - Random Access Memory. [Ram] Refers to electronic storage that can be read and written such that the speed of accessing any address in storage is independent of the address. The term "Random" distinguishes this type of storage from disk storage where the time taken to access the data is "cyclic" (i.e., it varies in cycles as the disk rotates) and tape storage where the time taken to access a given address is "sequential" (i.e., the entire tape must be read to find the data.)

RBOC - Regional Bell Operating Company. [Are Bock or Re bock (derisive)] One of the companies that resulted from the ATT divestiture of several operations. This division was based on the order of the Federal Court several years ago.

RGB - Red Green Blue. A type of video monitor interface.

RISC - Reduced Instruction Set Computer. [Risk] A class of computer system designed around the theory that most programs do not use very many of the available instructions in a normal Complex Instruction Set Computer. The theory suggests that RISC machines can be built that are much faster than CISC machines because they are more simple. As of this writing, there are no RISC machines that are PC compatible. The INTEL 80486 is internally a RISC design, one of the reasons that it is faster than a 80386 with the same clock speed. The series of machines made by Sun is probably the most well known family of RISC processors. They are mainly used as workstations for applications that require extensive computation.

RLL - Run Length Limited. One method of recording information on a hard disk. Half again as dense as the oldest PC method of disk recording, MFM. I.e., a 200 MByte hard disk with MFM recording would be 300 MBytes with RLL encoding. Since the data is packed more densely, this recording technique is slightly less reliable in demanding applications. It results in data transfer that is 50% faster than MFM. Although drives still use this technique, the controllers are now mostly imbedded in the drive so the controller is no longer known by this term.

ROM - Read Only Memory. [Rahm] Random access memory that could not be written, only read. Usually used to store programs, mostly related very closely to some hardware device in the machine. For example, video controllers always have ROM code on the board. See also CDROM.

RS-232(C) - [Are ess two thirty-two sea] An industry standard that defines an electrical interface for communicating between two computing devices in a bit serial manner. Also known as a serial port or a COMM port in the PC world. The latest specification is actually RS232(D), but it is a trivial change from RS-232(C), so don’t worry about the difference.

RTS - Request To Send. One of the signals in an RS-232 interface. It indicates that the DTE side is ready to transmit data.

SAA - System Application Architecture. An IBM standard for user program interfaces that operate identically across a wide variety of hardware systems.

SCODL - ???. One of many formats for storing graphics oriented data.

SCSI - Standard Computer System Interface. [Scuzzy] A class of controllers, mainly for hard disk. Faster than RLL & MFM, capable of handling devices other than disk drives, and controlling up to eight total devices (including CPU's). Not as fast as ESDI drives & controllers.

SDLC - Synchronous Data Link Control. An IBM bit serial data transmission protocol. Similar to HDLC.

SIMM - Single In-line Memory Module. A special form of RAM circuit used in most new PC's. It has no pins to bend accidentally as did the SIP's which preceded them..

SIP - Single In-line Package. A special form of RAM circuit used in some PC's. Like a DIP, but with only one line of pins.

SNA - Systems Network Architecture. A proprietary layered data transmission protocol used by IBM in their mainframe systems environments.

SNMP - Simple Network Management Protocol. A special protocol for use in networks to pass data around about the status or control of the network as opposed to passing data from one system to another. Used for error detection, control, and recovery and network management.

SPOOL - Simultaneous Peripheral Operations On-Line. [Spool] A process in which the operating system takes data from a program that is intended for an output device and saves it for later output. (Larger multi-user systems also SPOOL input data from card readers, but in the PC world the term applies almost exclusively to printer output.)

SPX - Sequenced Packet eXchange. The transport layer of protocol in a Novell network. Not actually used by very many programs.

SQL - Structured Query Language. [Ess que el or Sea' quell] A high level language used to interrogate a variety of data base systems. On a LAN a separate system can be dedicated to servicing SQL commands from many users. This is known as an SQL server.

SVGA - Super VGA (q.v.). A higher performing video interface. It typically begins at 800 x 600 pixels where VGA was 640 x 480.

.SYS - SYStem file extension. These files are device drivers to be loaded on top of DOS. The single exception is the file CONFIG.SYS. It is a normal ASCII text file that specifies the device drivers to be loaded.

T1 - Not actually an Acronym. Identifies 1.544 MBps leased lines available from phone companies. T2 to T4 lines are higher speeds.

TCP/IP - Transmission Control Protocol/Internetwork Protocol. A LAN protocol comprised of two layers that allow sharing of applications among systems at the transport and network layers. These layers allow terminal emulation and file transfer, among other things. They are hardware independent and can run over WAN’s as well as on LAN topologies. This protocol comes mostly from the UNIX and INTERNET worlds. This is the protocol family that is used on the Internet/ World-wide-web.

TDM - Time Division Multiplexing. Sending several signals over one medium by taking turns, sending first a part of one and then a part of another. (See FDM.) Channelized T1 lines are TDM circuits.

TELCO - TELephone Central Office or TELephone COmpany.

TIFF - ???. One of many formats for storing graphics oriented data. This format is commonly used by scanning devices.

TOP - Technical and Office Protocol. A version of the MAP LAN protocol designed by Boeing for office and engineering applications.

TSR - Terminate and Stay Resident. A class of programs. When these programs first run they leave a part of themselves in memory. They often attach themselves in such a way that they watch the keystrokes that the user types and can be activated to add functions that are not present in other applications. Examples are Screen to Disk capture (for graphics especially), Keyboard Macros, Notepads, LAN Print Spoolers, and disk cache buffer services.

TTL - Transistor/Transistor Logic. A type of digital electronic circuit. Very fast, but difficult to make into really complex circuits because of their relatively large size and high power requirements.

UDP - User Datagram Protocol. A part of the IP protocol family that allows programs to send packets of data without any guarantee of delivery. (TCP is used when delivery guarantee is needed.)

ULSI - Ultra-Large Scale Integration. Integrated Circuits made of Millions of transistors.

UPS - Uninterruptable Power Supply. Usually [Ups], sometimes [You pea ess] A device that is used between a PC or other data processing device and the power line to insure that small interruptions in the power do not disrupt the system. Normally contains a battery that will allow at least a few minutes operation of the system. This is usually enough time to shut down the system in an orderly way so that files are not corrupted.

USB - Universal Serial Bus. A new standard for connecting (relatively low speed) serial devices to PC’s.

V.nn - Not acronyms. Serial data communication standards released by the CCITT.

V.32 - Not an acronym. [Vee dot thirty-two] This is a specification for a class of medium speed modems.

V.42bis - Not an acronym. A specification for data compression in medium speed modems. (The "bis" means the second version.)

V.90 – Not an Acronym. A standard for modems that allows communication downstream at 56Kbps. Federal law currently limits the speed to about 53 Kbps. Upline speed is 33.6 Kbps.

VAN - Value Added Network. [Van] A network that offers services other than ordinary circuit switching.

VGA - Video Graphics Array. A color graphics video adapter with better resolution than an EGA adapter but less than the SVGA. Today this type of device is not very good for daily personal use because most software systems are designed for at least SVGA resolution. VGA monitors can be useful for server consoles, etc.

VLANs - Virtual LANs. A means of making a bridge or layer 2 switch operate as though there were multiple separate networks connected..

VLSI - Very Large Scale Integration. Integrated Circuits made of hundreds of thousands of transistors.

WHB - What’s Happening, Baby?

WORM - Write Once Read Mostly. [Worm] Memory that can be written once, then read as many times as desired. Today these devices are most often an optical disk. They are used primarily for archive storage of data that is no longer needed in online storage, but might be needed at a later date. Also a CD-recordable.

.WPG - Word Perfect Graphics file extension. One of many formats for storing graphics oriented data, in this case the format used by Word Perfect and Draw Perfect for storing graphics elements.

WYSIWYG - What You See Is What You Get. An adjective that describes PC systems that display on the screen the same format that they will print on paper.

XGA - ??? Graphics Adapter. The newest graphics adapter specification from IBM. Better resolution than and upward compatible with VGA. Equivalent to SVGA in resolution but roughly 2 times faster.

XNS - Xerox Network Service. Proprietary Ethernet peer to peer network protocol used by Xerox.

XOFF/XON - Names of ASCII characters that are sent between devices to temporarily suspend (XOFF) or resume (XON) transmission, usually because the receiver is busy or is running out of room for the data.

XT - One of a series of personal computers made by IBM. These systems were quite similar to the original PC, but featured up to 256K of RAM on the main system board as contrasted with 64K for the PC, and introduced support for hard disk drives.

CAU – C ????? Access Unit. IBM intelligent MAU for Token-Ring networks.

COW - Character Oriented Windows. An S ???

DDD - Direct Digital Dial. ???

DSL 56Kbps.

EMS - (.Ext).

HODS ?????

LATA - Local Area Transport Authority.

XDSL – XXX ????? Digital Subscriber Line (or Loop).

New RAM formats DIPPs? 56Kbps.

APPN – Advanced Peer to Peer Networking. An IBM protocol that ???

Table of Contents for 101 Secrets