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U3A in Bath Forum - Glossary

Introduction A glossary can't contain everything and still be short enough to be useful. If the term that's bothering you isn't here, type 'define:' followed by the term into Google's Search box. Some other useful sites are: http://www.itsafe.gov.uk/glossary.html Government website http://www.silverhairs.co.uk/glossary.htm 'Helpline for Silver Surfers' http://www.cryer.co.uk/index.htm An IT professional's hobby site http://www.geocities.com/ikind_babel/babel/babel.html Think 'Hitchhikers Guide' Babelfish http://www.jonstorm.com/glossary/ Another hobby site http://members.aol.com/shobansen3/ Computer help for people over 50 (from somebody who is, and is self-taught) Bold italic script is used to indicate words that are defined elsewhere in this glossary.

Basic Terms Application A program that you start in order to do Hardware Physical parts of the computer, such as the some work. Examples of applications are word HD or . Contrast software. processors, web browsers and e-mail readers. Internet A vast global network of computer networks Applications may be installed on the computer which operates world-wide using a common before delivery but are often obtained set of communications protocols (TCP/IP) and separately and installed later. An application sharing a common addressing scheme. The makes use of features of an Internet is a WAN. to print, read and write files, and access other pieces of hardware.Browser (or Web browser) Memory Internal storage areas in the computer. The A program you use to access information on term 'memory' identifies data storage that the Internet. Examples are Internet Explorer comes in the form of chips, whereas the word and Firefox. storage is used for memory that exists on tapes or disks. Moreover, the term 'memory' is Desktop The monitor screen, when it is displaying usually used as a shorthand for physical the background and icons (all windows memory, which refers to the actual chips minimised). One has to get used to the fact capable of holding data. also use that, while physical desktops are horizontal, virtual memory, which expands physical computer desktops are (near) vertical. memory onto a hard disk. Every computer E-mail Client (or Reader) An application program comes with a certain amount of physical that fetches and displays e-mail on the memory, usually referred to as main memory desktop. Examples: Outlook Express and or RAM. You can think of main memory as an Thunderbird. array of boxes, each of which can hold a single File A computer formed from a byte of information. A computer that has 1 collection of related data that is stored and megabyte of memory, therefore, can hold retrieved by an assigned name. A file in a about 1 million bytes (or characters) of computer system is a stream (sequence) of bits information. (The average English word stored as a single unit, typically in a file contains 4 characters so, allowing for spaces system on disk. and punctuation, 1MB is about 200,000 words or a reasonably-sized novel.) There are several Folder A collection of files with a unique in different types of memory: RAM, ROM, graphical user interfaces, such as Windows PROM, EPROM, and EEPROM. and MACs. Folders can hold files and other folders for organizational purposes. A list of operations or tasks available to a user in a given program, usually organized in some

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logical fashion on a menu bar. Users access a line interpreter. Graphical user interfaces allow function or command by selecting it from the you to enter commands by pointing and menu. Menus may 'drop down' or appear by clicking at objects that appear on the screen. right-clicking an on-screen object. PC ( or IBM PC) The first Monitor The most commonly used output personal computer produced by IBM was device with a screen for the visual display of called the PC, and increasingly the term PC information, text and graphics on a computer. came to mean IBM or IBM-compatible A monitor is different to a : it has a personal computers, to the exclusion of other much higher resolution and does not have a types of personal computers, such as Apple tuner for TV signals. Macintoshes. In recent years, the term PC has Mouse A hand-held for computers, become more and more difficult to pin down. involving a small object fitted with one or In general, though, it applies to any personal more buttons and shaped to sit naturally under computer based on an Intel, or Intel- the hand. The underside of the mouse houses a compatible, . For nearly every device that detects the mouse's motion relative other component, including the operating to the flat surface on which it sits. The mouse's system, there are several options, all of which 2-D motion is typically translated into the fall under the rubric of PC. motion of a on the display. Recently a Peripheral A device attached to the computer, such scroll-wheel has been added to speed up as a or scanner. down large web . Scroll Bar A graphical device used to change a user's Operating System (O/S) The most important view of the contents of a window. A scroll bar program that runs on a computer. Every consists of a slider, a trough, and scroll arrows. general-purpose computer must have an A window may have both a horizontal and operating system to run other programs. vertical scroll bar, depending on its size Operating systems perform basic tasks, such as relative to its contents. A user changes the recognizing input from the keyboard, sending view by moving the slider in the scroll area or output to the display screen, keeping track of by pressing one of the scroll arrows. These files and directories on the disk, and actions cause the view to scroll in the window controlling peripheral devices such as disk adjacent to the scroll bar. drives and printers. For large systems, the Software A program or set of instructions that operating system has even greater controls the operation of a computer. responsibilities and powers. It is like a traffic Applications and Operating Systems are cop – it makes sure that different programs and software. Contrast Data, Hardware. users running at the same time do not interfere with each other. The operating system is also Status Bar A component often found at the bottom of responsible for security, ensuring that windows in a GUI. It is often divided into unauthorized users do not access the system. sections, each showing different information. Operating systems provide a software platform It displays information about the current state on top of which other programs, called of its window, although some status bars have applications, can run. The application extra functionality. For example, many web programs must be written to run on top of a browsers have click-able sections that pop up a particular operating system. Your choice of display of security or privacy information. operating system, therefore, determines to a Taskbar The area across the bottom of the monitor's great extent the applications you can run. For screen that contains quick launch icons, a box PCs, the most popular operating systems is for each open application, tray icons, and Microsoft Windows, but others are available, clock. such as Linux. As a user, you normally interact with the operating system through a Title Bar The bar across the top of a window that set of commands. The commands are accepted consists of the Window menu button, the Title and executed by a part of the operating system Area, and the Window-Control Buttons called the command or command (Minimise, Maximise and Close).

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Tool Bar A frame or special area below the Menu Bar that contains a set of icons. Clicking on an icon executes a command or causes an action. Window The box on your screen around the graphics produced by a program. Contains the title bar, scroll bars, resize point and status bar.

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More Advanced Terms AGP (Accelerated Graphics Port) An interface serial. When used in reference to PCs, the specification developed by Intel Corporation, term bus usually refers to the parallel internal designed especially for the high throughput bus that connects all the internal computer demands of three-dimensional (3-D) graphics. components to the CPU and main memory. Being phased out in favour of PCI-E. There's also a parallel expansion bus that Bandwidth The amount of data that can be enables expansion boards to access the CPU transmitted in a fixed amount of time. For and memory. All buses consist of two parts: digital devices, the bandwidth is usually the data bus transfers actual data whereas the expressed in bits per second (bps) or bytes per address bus transfers information about where second (Bps). For analogue devices, the the data should go. The width (size) of a bus bandwidth is expressed in cycles per second, determines how much data can be transmitted or Hertz (Hz). The bandwidth is particularly at one time. For example, a 16-bit bus important for I/O devices. For example, a fast transmits data 16 bits at a time. Every bus has disk drive can be hampered by a bus with a a clock speed measured in MHz. A fast bus low bandwidth. This is the main reason that allows data to be transferred faster, which new buses, such as AGP and PCI-E, have makes applications run faster. PCI is the usual been developed for the PC. bus on today's PCs. Nearly all PCs made today also include a local bus that connects directly BIOS (Basic Input/Output System) The BIOS is to the CPU for data that requires especially built-in software that determines what a fast transfer speeds, such as data (AGP computer can do without accessing programs or PCI-E). A different bus, either IDE or from a disk. On PCs, the BIOS contains all the SATA (serial), is used for connecting storage. code required to control the keyboard, display Older Apple Macintosh computers use a bus screen, disk drives, serial communications, and called NuBus, but newer ones use PCI. a number of miscellaneous functions. The BIOS is typically placed in a ROM chip on the Byte (binary term) a unit of storage capable of motherboard (it is often called a ROM holding a single character. On almost all BIOS). This ensures that the BIOS will always modern computers, a byte is equal to 8 bits. be available and will not be damaged by disk Large amounts of memory are indicated in failures. It also makes it possible for a terms of Kilobytes, Megabytes and Gigabytes. computer to boot itself. Modern PCs have a Caching A technique of temporarily storing flash BIOS, e.g. an EEPROM which means frequently accessed data in random access that the BIOS can be updated if necessary. memory (RAM) or in a special area of a hard Bit Fundamental unit of computer information. disk drive, to reduce the time required to read Computers use binary arithmetic, so a bit can and write data. only have the value 1 or 0. CD-R (Compact Disk Recordable) A is Boot (Bootstrap – as in 'pulling oneself up by one's made from polycarbonate with one or more bootstraps') To load the first piece of software metal layers capable of storing digital that starts a computer. Because the operating information. One of the problems with CD-R system is essential for running all other disks is that you can only write to them once. programs, it is usually the first piece of CD-RW (CD-ReWritable disk) a type of CD disk that software loaded during the boot process. enables you to write onto it in multiple BPS (Bits Per Second) the standard measure of data sessions. With CD-RW drives and disks, you transmission speeds. NB Lower-case 'b' can treat the optical disk just like a floppy or signifies 'bit', upper-case 'B' signifies 'Byte'. hard disk, writing and over-writing data multiple times. Bus A collection of wires forming a highway on which data travels from one part of a computer Clicking The action of depressing a to another. A bus may be either parallel or when the on-screen pointer has been used to select an item. Clicking may be done with the

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left mouse button or the right (left-click, right- also are two additional standards for DVD-R click). 'Double-clicking' means two clicks of disks: DVD-RG for general use, and DVD-RA the left mouse button in quick succession. for authoring, which is used for mastering CPU () The CPU is the DVD video or data and is not typically brains of the computer. Sometimes referred to available to the general public. simply as the processor or central processor, DVD+RW, DVD-RW (DVD ReWritable) a re- the CPU is where most calculations take place. recordable DVD format similar to CD-RW. In terms of computing power, the CPU is the The data on a DVD+RW disc can be erased most important element of a computer system. and recorded over numerous times without On personal computers and small damaging the medium. workstations, the CPU is housed in a single DVI () A standard that chip called a microprocessor. Two typical defines the digital interface between digital components of a CPU are the arithmetic logic devices such as projectors and personal unit (ALU), which performs arithmetic and computers. For devices that support DVI, a logical operations and the control unit, which digital to digital connection can be made that extracts instructions from memory and eliminates the VGA conversion to analogue decodes and executes them, calling on the and thereby delivers an unblemished image. ALU when necessary. EDO (Extended Data Out DRAM) A faster type of Data Information stored on the computer system, dynamic random access memory. Only found used by applications to accomplish tasks. on old machines. DDR (Double Data Rate synchronous DRAM) a EEPROM (Electrically Erasable Programmable type of SDRAM that supports data transfers on Read-Only Memory) An EEPROM is a both edges of each clock cycle (the rising and special type of PROM that can be erased by falling edges), effectively doubling the exposing it to an electrical charge. memory chip's data throughput. DDR-SDRAM also consumes less power, which makes it EIDE (Enhanced Integrated Drive Electronics) EIDE well-suited to notebook computers. is a newer version of the IDE mass storage device interface standard developed by DIMM (Dual In-line Memory Module) a small Western Digital Corporation. circuit board that holds memory chips. The Pentium processor requires a 64-bit path to EPROM (Erasable Programmable Read-Only memory. A DIMM has a 64-bit path, so you Memory) An EPROM is a special type of can install memory one DIMM at a time PROM that can be erased by exposing it to (unlike SIMMs). ultraviolet . Distribution A collection of open source soft-ware, (Named from the concept of the ether.) One based around Linux, tested to ensure that all of the earliest and least expensive network elements will work with each other, and with types, Ethernet is the most widely used LAN an easy mechanism for obtaining updates. technology. It can transmit information between computers at speeds of 10 or 100 Document A file created using an application. For Mbps over twisted pairs of wires, or 1,000 example, you might create a text document Mbps over optical fibre. Workstations send using a word processing application e.g. MS- packets of data, but only when they have Word or a picture document using a graphic determined that no other workstation is application e.g. Paint Shop Pro. transmitting. DRAM (Dynamic Random Access Memory) a type EULA (End User License Agreement) The license or of memory used in most personal computers. contract between you as a user of a piece of DVD+R, DVD-R (DVD Recordable) a recordable software and the vendor or provider of the DVD format similar to CD-R. A DVD+R or software. Usually displayed once only as a DVD-R can only record data once and then the step in the installation of a program such that data becomes permanent on the disc. The disc the EULA must be accepted for installation of cannot be recorded onto a second time. There the software to continue. Sometimes it appears

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on the inside of a package that must first be effects and transforms objects every time a 3- opened. Often very restrictive. D scene is redrawn. These are mathematically- FAQ A list of Frequently Asked Questions and their intensive tasks; removing this burden from the answers. The first place to go when looking for CPU frees it up to perform other jobs. help on a topic. GUI (Graphical ) The screen that we FOSS (Free Open Source Software) See Open see most of the time on our computers, where Source. we interact using WIMP. Replaced the text screen used on early PCs, referred to as a DOS Firewall That part of an operating system that screen or a Command Line Interface (CLI). controls what type of messages are allowed into and out of a machine. It is important not to HD or HDD (Hard Drive or ) The allow those types that you have no need for, as usual bulk storage mechanism in a PC. that will greatly reduce you risk of attack by Consists of one or more rigid aluminium discs malware. The firewall implements the policy with a magnetic coating rotating rapidly in a the user defines to control access to different sealed enclosure. Incredibly accurately networks with different levels of trust. positioned electro-magnetic 'heads' 'fly' very close to, but not touching, the magnetic surface FireWire (1394) A very fast external bus standard to read or write data to it. (A head touching the that supports data transfer rates of up to surface of the disk is referred to as a 'crash' and 400Mbps (in 1394a) and 800Mbps (in 1394b). usually results in physical damage leading to The name FireWire is trademark of Apple Inc. the partial or complete failure of the HD). A single 1394 port can be used to connect up Many disk drives improve their performance 63 external devices. In addition to its high through a technique called caching. IDE, speed, 1394 also supports isochronous data – SCSI and SATA are the most common delivering data at a guaranteed rate. This interfaces used for passing data between hard makes it ideal for devices that need to transfer disk and computer. high levels of data in real-time, such as video devices. Although extremely fast and flexible, Hot Plugging is the practice of plugging 1394 is also expensive. Like USB, 1394 or components into, or unplugging them from, supports both Plug-and-Play and hot a 'live' computer system. Unless the computer plugging, and also provides power to is specially designed, hot plugging may cause peripheral devices. damage and will, almost certainly, cause a malfunction. However, the USB and 1394 Gb (Gigabyte) or GB (GigaByte) 'Giga' in metric interfaces are designed to allow hot plugging; terminology means 1,000,000,000. However, special software is provided with some in computer terms it is 230 or 1,073,741,824. to allow the similar 'hot swapping' of optical GPL (General Public Licence) A software license, disk drives. originally written by Richard Stallman for the HTML (Hyper-Text Mark-up Language) The GNU project (a project to create a complete 'language' in which web pages are described. A free software operating system); now browser can read the description, map it onto maintained by the Free Software Foundation. the available window space and place pictures It has become the most popular license for free and text accordingly. or open source software. The purpose of the GPL is to grant any user the right to copy, I/O (Input/Output) The term I/O is used to modify and redistribute programs and source describe any program, operation or device that code from developers that have chosen to transfers data to or from a computer and to or license their work under the GPL – provided from a peripheral device. Every transfer is an that, if a modified version is distributed, the output from one device and an input into source must be distributed too. another. Devices such as keyboards and mice are input-only devices while devices such as GPU (Graphic Display Unit) Used primarily for 3-D printers are output-only. A writeable CD drive applications, a is a is both an input and an . single-chip processor that creates lighting

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Icon A small picture that is linked to an application, operating system. Loosely, it is sometimes folder or file so that it can be easily located extended further to refer to the entire body of and opened. Open Source software. IDE (Integrated Drive Electronics) An interface for Local bus A data bus that connects directly, or almost mass storage devices, in which the controller directly, to the microprocessor. Although local is integrated into the disk or CD-ROM drive. buses can support only a few devices, they ISA (Industry Standard Architecture) The bus provide very fast throughput. Modern PCs use architecture used in early IBM PCs. The ISA a PCI local bus; old machines used an ISA specification was updated to enable Plug and bus. Play in 1993. Legacy hardware only. Malware The generic term for worms, viruses, Kb (Kilobit), KB (KiloByte) 'Kilo' in metric spyware, adware, etc. which are programs that terminology means 1,000. However, in are unwanted on a machine. They can damage computer terms it is 210 or 1,024. data, steal data or identities, continually try to sell goods and services, route networks LAN (Local Area Network) A computer network through expensive lines, etc. They can arrive that spans a relatively small area. Most LANs through e-mail, by browsing web-sites, or in are confined to a single building or group of some cases directly across the network. buildings. Most LANs connect workstations and personal computers. Each node Mb or MB (Megabits or MegaBytes) 'Mega' in metric terminology means 1,000,000. (individual computer) in a LAN has its own 20 CPU with which it executes programs, but it However, in computer terms it is 2 or also is able to access data and devices 1,048,576. anywhere on the LAN. This means that many Motherboard The main circuit board of a users can share expensive devices, such as . The motherboard contains the laser printers, as well as data. Users can also connectors for attaching additional boards. use the LAN to communicate with each other, Typically, the motherboard contains the CPU, by sending e-mail or engaging in chat sessions. BIOS, memory, mass storage interfaces, serial There are many different types of LANs, and parallel ports, expansion slots, and all the being the most common for PCs. controllers required to control standard Most Apple Macintosh networks are based on peripheral devices, such as the display screen, Apple's AppleTalk network system, which is keyboard, and disk drive. Collectively, all built into Macintosh computers. LANs are these chips that reside on the motherboard are capable of transmitting data at very fast rates, known as the motherboard's chipset. On most much faster than data can be transmitted over a PCs, it is possible to add memory chips telephone line; but the distances are limited, directly to the motherboard. You may also be and there is also a limit on the number of able to upgrade to a faster PC by replacing the computers that can be attached to a single CPU chip. To add additional core features, you LAN. may need to replace the motherboard entirely. Legacy A euphemism for 'obsolescent' or 'obsolete'. Motherboard is sometimes abbreviated as For example, the drive is 'legacy 'mobo'. hardware'. Few new PCs have one and PC ODF (OpenDocument – short for OASIS Open World has recently announced that it will no Document Format for Office Applications) is a longer stock the diskettes. file format used for electronic documents such Linux Strictly, Linux is a kernel (the core of an as memos, reports, books, spreadsheets, charts, operating system) created by Linus Torvalds and presentations. OpenDocument is both an and developed with the help of collaborators OASIS Standard and a published ISO and IEC worldwide, linked by the Internet. However, International Standard – ISO/IEC 26300:2006. the term Linux tends to be used for this core The OpenDocument specification is freely together with all of the associated tools that available and implementable. turn it into a complete and very powerful

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Open Source A method of developing software platform used to create it. PDF files are where the source code is made freely available compact and complete, and can be shared, over the Internet for use or modification as viewed, and printed by anyone with suitable users or other developers see fit. (Historically, software e.g. the free 'Adobe Reader'. the makers of proprietary software have Plug-and-Play A feature that enables the operating generally not made source code available.) system to recognise when new hardware has Modifications are fed back to the originators been connected and to configure itself such for incorporation, thus improving the overall that the new hardware can be used. product. Open Source software is distributed under a licence, such as the GPL, that allows Pointer The graphical image of a cursor that appears copying and use, but maintains the on the workspace and is controlled by the contributors' copyrights. current location of a mouse or other pointing device. Also referred to as mouse pointer. Optical Disk Generic term for CDs and , based on the use of lasers to write to/read from them. Port 1) A means of connecting to the computer. Each computer has a range of physical ports, such as Parallel In computer terms a bus in which there is one VGA or DVI (for the monitor), serial and wire per bit of information – so a 32-bit parallel (Centronics) – both now legacy and parallel bus would have 32 wires. Contrast replaced by USB, 1394, PS/2 (for mouse and serial. keyboard, also legacy and replaced by USB). Parity A simple error detection scheme. The number 2) A means to enable data moving between the of '1' bits in the data is counted and an computer and the Internet to be associated additional bit is set to either '1' or '0' depending with the correct program. on whether the result was even or odd. 3) The process of moving a program from one PCI (Peripheral Component Interconnect) a local computer to another which runs a different bus standard developed by Intel Corporation, operating system. but not tied to any particular family of PROM (Programmable Read-Only Memory) A . It progressively replaced the PROM is a memory chip on which you can previous ISA expansion bus in PCs. PCI is store a program. But once the PROM has been also used on newer versions of the Macintosh used, you cannot wipe it clean and use it to computer. store something else. Like ROMs, PROMs are PCI-E or PCIe (Peripheral Component Interconnect non-volatile. Express) Next generation serial bus interface, Protocol (or Communications Protocol) The superseding AGP for graphics cards. definition of the meaning of messages that PDF (Portable Document Format): A file format pass between two computers on a network. created by Adobe Systems based on its Without an agreed protocol no messages could PostScript® page description language (used be transmitted or understood. Because it is by many printers). PDF is a de facto standard essential that all nodes on the Internet for the secure and reliable distribution and understand the signals in the same way, exchange of electronic documents and forms protocols are rigidly standardised. around the world. PDF files are platform- and RAM (Random Access Memory) a type of computer device-independent, and preserve the fonts, memory that can be accessed randomly; that images, graphics, and layout of any source is, any byte of memory can be accessed document, regardless of the application and without touching the preceding bytes. RAM is The starting point for this glossary was the list of terms in a glossary compiled by Andy Pepperdine for the talks he gave on FOSS, together with another list from a (slightly out-of-date) glossary put on the web by a computer consultancy firm, Kulnis. Thank you both. I have removed some of the more esoteric definitions, simplified and updated others, and added definitions for some of the terms that were treated as assumed knowledge. I have used Google's 'define:' facility extensively so extensively that I alone must take the blame for any lack of clarity or accuracy in the definitions reproduced in this document. Mike Godfrey

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the most common type of memory found in storage interface. It uses 7 wires instead of the computers and other devices, such as printers. traditional 40 wires for IDE/ATA interfaces. There are two basic types of RAM: dynamic SCSI (Small Computer System Interface) SCSI is a RAM (DRAM) and static RAM (SRAM). The parallel interface standard used for attaching two types differ in the technology they use to peripheral devices such as disk drives and hold data, dynamic RAM being the more printers to larger computers e.g. servers. It is common type. Dynamic RAM needs to be rarely used on desktop PCs, but was used on a refreshed thousands of times per second. Static number of Apple Macintosh computers. SCSI RAM does not need to be refreshed, which provides fast data transmission rates (up to makes it faster; but it is also more expensive 80MBps) and you can attach many devices to a than dynamic RAM. Both types of RAM are single SCSI port, so that SCSI is really an I/O volatile, meaning that they lose their contents bus rather than simply an interface. when the power is turned off. In common usage, the term RAM is synonymous with SDRAM (Synchronous Dynamic Random Access main memory, the memory available to Memory) a type of DRAM that can run at programs. For example, a computer with 8MB much higher clock speeds than previous types RAM has approximately 8 million bytes of of memory. SDRAM actually synchronizes memory that programs can use. To be precise, itself with the CPU's bus and is capable of RAM should be referred to as read/write running at 133 MHz, about twice as fast EDO RAM. DRAM. SDRAM replaced EDO DRAM, but is now legacy hardware. RDRAM (Rambus DRAM) a type of memory developed by Rambus, Inc. Faster than the Serial An electronic connection between two devices SDRAM but overtaken by other technologies. in which digital data is transferred one bit after Unlucky owners of PCs fitted with this another, rather than several bits at a time. technological blind alley pay higher prices for (Think of a railway train.) Compare parallel. additional RAM. A computer that delivers information and Resolution (Short for 'Screen Resolution') The software to other computers linked to it by a width and height of the visible picture on a network. , determined by the Shortcut An icon or file that serves only to point computer's graphics card. Common video towards another file, used most often in the adapters for PC monitors are VGA (640 x MS-Windows desktop or Start Menu. (On the 480), Super VGA (800 x 600), XGA (1024 x Mac, the same idea is called an alias.) You 768) and Wide XGA (WXGA) (1280 x 768). create a shortcut by right-clicking on a file or ROM (Read Only Memory) on icon, then choosing 'Make Shortcut' from the which data has been pre-recorded. Once data pop-up menu. has been written onto a ROM chip, it cannot SIMM (Single In-line Memory Module) a small be removed and can only be read. Unlike main circuit board that can hold a group of RAM memory (RAM), ROM retains its contents chips, either 8 (on Macintoshes) or 9 (on PCs). even when the computer is turned off, so ROM On PCs, the ninth chip is often used for parity is referred to as being non-volatile. Most error checking. A SIMM has a 32-bit path to personal computers contain a small amount of the memory chips; because the Pentium ROM that stores critical programs such as the processor requires a 64-bit path to memory, program that performs start-up diagnostics and you need to install SIMMs in pairs. boots the computer. In addition, ROMs are used extensively in calculators and peripheral Storage Holding program instructions and data for devices such as laser printers, whose fonts are use by the computer. Temporary storage while often stored in ROMs. PROM, EPROM and the computer is running is provided by RAM, EEPROM are variants of a ROM. and permanent storage through optical disk, hard disk or . SATA (Serial Advanced Technology Attachment) An evolutionary replacement for the IDE physical URL (Uniform Resource Locator) The 'address' or location of a web page on the Internet.

10 February 2007 9/10 U3A in Bath Computer Forum - Glossary

USB (Universal Serial Bus) an external bus standard The term VGA is often used to refer to a that is expected to completely replace serial resolution of 640×480, regardless of the and parallel ports. A single USB port can be hardware that produces the picture. It may also used to connect up to 127 peripheral devices, refer to the 15-pin D-subminiature VGA such as mice, modems, and keyboards. USB connector which is still widely used to carry also supports Plug-and-Play installation and analogue video signals of all resolutions. VGA hot plugging. USB 2.0 is a much faster is being superseded by DVI. extension of USB 1.1, theoretically supporting WAN (Wide Area Network) A system of LANs data rates up to 480Mbps. USB 2.0 uses the inter-connected over any distance via same cables and connectors as USB 1.1. telephone lines and radio waves is called a VGA (Video Graphics Array) An analogue graphics wide-area network (WAN). The Internet is a display system for PCs developed by IBM. WAN. VGA is the lowest common denominator that WIMP The elements of a Graphical User Interface all PC graphics hardware supports prior to a (GUI) – Windows, Icons, Menus, Pointers. device-specific driver being loaded.

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