Glossary of computer terms used in these pages.

Just a quick list of acronyms and specialist terms I've noticed I've used in these pages. If there is a demand, I'll expand it later, but it probably would be easier (and likely more accurate) to point this page at some existing computer dictionary. A good online encyclopedia is at

Analog to Digital Converter (see also DAC). Change a continuously varying value to a discrete and very limited number.
Asymetric Digital Subscriber Line. A method of cramming fast digital data down a Plain Old Telephone System line. Hell will freeze over before it becomes available in any area that doesn't have data over cable as a competitor (it kills Telstra profiteering on expensive ISDN lines). (2003) I was wrong. Hell didn't freeze over. Telstra just made the download limit so low it isn't worth having.
Application Programming Interface. Set of interfaces, the characteristics of which are known to programmers from the company who made the API, and guessed by other companies.
Application Specific Integrated Circuit (chip). A chip that hides design features from your competitors.
Asynchronous Trasfer Mode. 53 byte fixed length packets, independent of transfer rates. Sets up end to end virtual circuits and negotiates a quality of service during connection setup.
big endian, or human readable
Stores the most significant byte of any multi-byte data at the lowest memory address, which is also the address of the entire field. See also little endian. 68k and PowerPC CPUs are big endian, and most internet protocols like TCP assume data is big endian. Intel x86 CPUs are however unfortunately little endian. Example char C1=1; char C2=2; short S=255; long L=0x44332211; memory dump 01 02 FF 00 44 33 22 11
Binary Format for Scenes, language for MPEG-4
binary digit (choice of 0 or 1) There are 10 types of people. Those who understand binary, and those who do not.
Boot Protocol
Common Gateway Interface. Used for online forms on web.
Concentration Highway Interface
Complementary Metal Oxide Semiconductor (transistor etc)
Central Processor Unit (heart of computer)
Carrier sense multiple access collision detection. All attached nodes listen for collisions, and backoff it one occurs. Limits cable distance; higher frequency, lower distance.
Digital to Analog Converter (see also ADC) Partially reverses the damage done by ADC, especially in music recording.
Dynamic Host Configuration Protocol.
Dynamic Hypertext Markup language. React badly to browser being used.
Direct Memory Access (not via CPU)
Domain Name System. Turns an internet address into an IP number (like a phone number for the internet). Asks a DNS server on port 53.
Dynamic Random Access Memory (needs a refresh cycle)
Digital Signal Processing
Digital Versatile Disk
Extended Data Out
LAN standard uses IEEE 802.3 CSMA/CD and 10 Mbps transfer. Physical standards include 10Base5 (thick Ethernet), 10base2 (thin or cheapernet on RG58C coax with BNC connectors), 10baseT (twisted pair, at 10 Mbps with RJ45 connectors similar to phone RJ11 connectors). Fast Ethernet (IEEE 802.3u is 100 Mbps, RJ45 connectors, on Category 5 twisted pair). Gigabit Ethernet (IEEE P802.3z 1000 Mbps).
A method of presenting consistent navigation information on your site in a way that annoys visitors by breaking printing facilities, and stuffing up the back button on older browsers. Divides computer screen into multiple windows in a way that wastes most of your display space.
File Transfer Protocol. Moves files over a network.
Compuserve's Graphic Interchange Format, used by web browsers. Limited to 256 colours. Supports animation and transparency, but is owned by Unisys who can charge fees to use it.
High Definition TeleVision
Hexadecimal, numbers to base 16 (0 to 9 then A, B, C, D, E, F)
The language these pages are written in. See the standards for how to do HTML at
Internet protocol. Connectionless (datagram) service to higher transport protocol (usually TCP).
Input Output
InfraRed Data Association
Integrated Services Digital Network. Runs over a plain phone line at 128 kbps, so the phone company charges a fortune for it. The major reason we don't have ADSL available.
Internet Service Provider. Connects you to the internet (for a fee).
Joint Photographic Expert Group also jpg. Good for photographs, but uses a lossy compression method so pictures are somewhat degraded. Quality can be adjusted to at the expense of file size. Used extensively by web browsers.
JPEG 2000
Uses wavelet compression up to 40 times more effectively than current JPG (which uses discrete cosine transformation). May become popular is browser makers take it up.
kilo Hertz (variously 1000 or 1024 = 2^10)
Local Area Network
Liquid Crystal Display
little endian
Stores the least significant byte of any multi-byte data at the lowest memory address, which is also the address of the entire field. See also big endian Intel x86 chips are little endian, which is rather unfortunate, as most internet protocols like TCP assume data is big endian, or human readable. Example char C1=1; char C2=2; short S=255; long L=0x44332211; memory dump 01 02 FF 00 11 22 33 44
Low Profile Quad Flatpack (chip package)
MAC (in CPU)
Multiplier Accumulator, hardware to speed up some types of calculations
Media Access Control, unique 48 bit NIC card number
Megahertz (variously 1,000,000 if a drive maker or 1,048,576 = 2^20)
Multipurpose Internet Mail Extensions. Standard for transferring non-mail files via mail. Used for delivering porn and viruses.
Million Instruction Per Second, also name of CPU design company owned by Silcon Graphics
Popular name for audio compression standard described by the third of three layers defined in MPEG-1 and MPEG-2. Actually MPEG-1, Audio Layer-3.
Motion Picture Experts Group, founded in 1988. Sets standards for broadcast video. MPEG-1 in 1992 defined an efficient means of storing video and sound (it is used in VCDs). MPEG-2 is used by DVD video and HDTV. Object oriented vector based MPEG-4 from 1999 was designed for low bandwidth internet communication and is based on Apple's QuickTime. Borrows from VRML. Uses BIFS as a language for describing scenes. MPEG-7 is for describing multimedia content via metainformation. It uses descriptions similar to XML (politics involved). There is no MPEG-3.
milli Watt, measure of power (1/1000 of a Watt)
Network Interface Card. Connects host computer to a network.
no operation, do nothing instruction to CPU
Personal Computer Memory Card International Association (now known as PC Card) or people can't memorise computer industry acronyms
picture cell (one dot on a display)
Personal Digital Assistant, what Apple said the Newton would be
Phase Locked Loop
Portable Network Graphics. The W3C recommended web browser format. Royalty free, superior in many ways to GIF or JPG. Lossless compression system, 48 bit colour support (not implemented in browsers). Variable transparency, sophisticated interlacing, but no animation. Files are usually too large for web work without tweaking.
Peak to Peak (usually AC voltages).
Point to Point Protocol. Allows your computer to pretend to be on the internet via a phone line and modem.
Public Switched Telehone Network (sometimes also called POTS - plain old telephone service).
Random Access memory (computer memory)
Proprietary Rambus designed memory, promoted by Intel. Not as fast as they hoped, and much more expensive than it should be. Avoid it for now (mid 2000) and use open standard SDRAM.
Reduced Instruction Set Computer
Read Only Memory (may be used by BIOS in computer)
Real Time Clock
Space Communications Protocol Suite. Extensions to TCP/IP to allow for low bandwidth and long latency. Windowing is delayed. Hole filling of missing data blocks may be requested individually. 8 bit network addresses permitted. Does not interoperate with TCP/IP.
Small Computer System Interface, now with many variations. SCSI-1 (narrow SCSI) is 5 megabyte per second, 10 MHz bus clock, 8 bit data, 50 way cable. SCSI-2 (Fast SCSI) pushed that to 10 Mps. These two used asynchronous transmissions. Ultra SCSI doubled the bus clock to 20 MHz, data to 20 Mps, and like all later SCSI was synchronous. Fast wide SCSI moved to a 16 bit data path and 68 pin connector, Ultra Wide to 40 Mps, Ultra2 SCSI to 80 Mps and Ultra160 used two bits per data clock to reach 160 Mps. Remember a 7200 rpm drive can transfer 20 Mps in sequential reads, you can stack up to 15 SCSI drives, and your operating system must be able to handle SCSI correctly (Windows 9x does not) to get full speed from it. Suits servers.
Synchronous DRAM (more advanced version of RAM)
Macromedia programs designed to waste all available bandwidth on the web by filling narrow pipes with content free sound and vision. Sort of like a TV show designed by an advertising director.
Serial Peripheral Interface
Splash Screen
Also known as an Entry or Front Door. A web page designed to slow the entry of visitors to your site, by forcing them to wait for a bunch of content free graphics to download.
Static Random Access Memory (does not require refresh cycle)
Scalable Vector Graphics, XML based, expected to be used as a web graphics standard eventually.
Transmission Control Protocol/Internet Protocol. Lets different computers speak the same language.
Trivial File Transfer Protocol. Self contained way of transferring files, designed for small dumb devices. Used to boot some workstations. Allows a device to ask on port 69 for a named file to be transmitted to it, usually a binary image file for a netboot. As each packet arrives TFTP sends an acknowledgment.
Uniform Resource Locator. Addresses on the internet.
Virtual Reality Modeling Language
API standard to provide IP and Internet access under Windows. Available for Windows 3.11 (try Trumpet) and all following versions. Check for details.
I hope you have enjoyed