Glossary: I

This page contains glossary terms beginning with the letter I.
!-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Word or Term Description or Explanation
I/O Input/Output
I/O podule Acorn's (dual width) interface card that provides RISC OS computers with some of the many interface facilities that were standard on the BBC Micro range of computers - interfaces include user port, parallel port, analogue post and 1MHz bus
ICA Independent Computing Architecture (Citrix Systems) - previously called Intelligent Console Architecture
ICMP Internet Control Message Protocol - a protocol used on the Internet to send control information, e.g. ping uses this to send an "Echo_Request"
Iconbar the strip along the bottom of the computer screen that contains icons for devices (to the left) and applications (to the right) that are currently available to the user
Icons small pictures representing devices, files, directories, applications, etc.
IDC Insulation Displacement Connector - this refers to a connector where the connection between the contacts and the individual wires is made by squeezing a row (or usually two rows) of sharp metal teeth onto a ribbon cable so that the teeth cut into the insulation and make contact with each individual wire
IDE Integrated Drive Electronics - an electronic standard method of connecting one or two hard drives to a computer system - the standard was set up to provide a simpler and cheaper means of connecting hard drives to IBM and compatible computers than was currently available
IDTV Integrated digital television - the set-top box technology is integrated into the casing of a television casing to eliminate the need for a separate receiver decoder
IEEE488 an interface standard for connecting scientific instruments to computers as agreed by the Institute of Electrical and Electronic Engineers (USA) - 488 is the number of the document - usually called IEEE interface, but also HPIB and GPIB for Hewlett Packard ..... and General Purpose ...., originally designed by HP - it is an 8-bit data bus, allowing up to 16 devices to be addressed, with handshake and interrupt lines - Intelligent Interfaces make a very good IEEE interface for the RISC OS computers, but it won't work with the Acorn Unix boxes because of interrupt latency
IIC or I2C Phillips' proprietary 2-wire serial bus interface - one wire is a clock and the other carries serial data - used internally in Archimedes computers for the real time clock and the CMOS RAM - difficult to use externally because of buffering problems (it is very difficult to buffer a bidirectional line) - IIC is used in TVs and radios, HiFis etc.
Image processing if an image is stored on a computer as binary data (such as a sprite file) it is possible to manipulate the data mathematically to enhance, distort, translate or otherwise modify the picture in controlled ways
IMAP Internet Mail Access Protocol - this is a networking protocol which allows users to manipulate and read the contents of mail folders held on a remote server - unlike with the POP protocol, the mail continues to reside on the remote machine - this approach has advantages in an environment where users move from machine to machine so that transferring an individual's mail to a particular client machine would not be appropriate - the protocol is formally specified by Internet RFC 1176 - there is a good document which describes these which you can get from ftp://ftp.cac.washington.edu/mail/imap.vs.pop
Inkjet printer this is a type of printer where the patterns on the paper are generated by squirting ink through a series of tiny nozzles in the print head
Input focus the input received from the keyboard can be directed to one and only one window at a time - the window currently receiving information from the keyboard is said to have the input focus - this is indicated by the title bar of the window changing from grey to yellow
Intel Corporation a major manufacturer of microprocessors for PCs, e.g. the 80286-80486 range and their proprietary Pentium/Pentium II
Interlace build up a picture on a monitor screen using two passes, each displaying alternate lines, the aim being to reduce flicker effects
Internet an interconnected network of networks - the Internet exists purely as a large group of machines that pass messages to each other, sites linking themselves in because they found it useful - remember when using the Internet that you are piggy backing on other peoples efforts and paying nothing for it, so be polite because they could easily decide to stop passing your messages through - there is no one organising it and hence no one to complain to if you don't like it - the Internet is probably the world's most successful anarchy!
Internet address see IP address
Internet Explorer a browser developed by Microsoft to compete with Netscape's Navigator, and its methods of distribution have led to some charged confrontations between Microsoft and the US Department of Justice
Internet Protocol
Suite
the set of protocols which includes TCP, UDP and IP - it is also often (misleadingly) referred to as TCP/IP - originally developed in the 1970s and early 1980s by the U.S. Defense Advanced Research Projects Agency for the Arpanet, precursor of the Internet
Interpreter a program that converts each instruction of a high level language such as Basic into executable machine code line by line, as the program in the high level language proceeds (see Compiler for more explanation) - every RISC OS computer contains a Basic interpreter
IOC Input/Output Controller - the I/O chip used on pre-RiscPC Acorn computers was called IOC
IOMD Input Output Memory Device - this is a computer chip designed by ARM Ltd which allows ARM processors to control input/output devices and to access memory
IP (1) Internet Protocol - the network protocol responsible for passing data packets from one host to another - each packet contains the IP address of both the source and destination hosts - IP is regarded as unreliable because individual packets may get lost as they wander around the Internet - hence TCP is usually to control it if reliability is important
IP (2) Information Provider - a company that provides Internet access on a commercial basis
IP address a unique 32-bit address assigned to a host connected to the Internet (usually this is a static allocation, but some dial-up Internet providers assign IP addresses dynamically when you log on.) - the IP address is usually presented in dotted-decimal format (e.g. 123.45.67.89), where each number represents eight bits of the address - the first part of the address is assigned exclusively to an organisation by the Network Information Center (NIC) in the United States - the use of the individual addresses within this address space is then devolved to the organisation itself
IRC Internet Relay Chat - a service operated on certain hosts which allows multi-party online conversations - it allows users to 'chat', by typing text, in real time - it is the Internet equivalent of CB radio - the user runs an IRC client and connects to an IRC server using a command such as /server stork.doc.ic.ac.uk - heshe then selects a particular channel with /join #channel or similar
IrDA Infrared Data Association, Walnut Creek, CA, http://www.irda.org - a membership organization founded in 1993 and dedicated to developing standards for wireless, infrared transmission systems between computers - with IrDA ports, a laptop or PDA can exchange data with a desktop computer or use a printer without a cable connection - IrDA requires line-of-sight transmission like a TV remote control - IrDA products began to appear in 1995 - the LaserJet 5P was one of the first printers with a built-in IrDA port
IrDA is comprised of the IrDA Serial IR physical layer (IrDA-SIR), which provides a half-duplex connection of up to 115.2 Kbps - this speed allows the use of a low-cost UART chip; however, higher non-UART extensions for 1.15 and 4 Mbps have also been defined - IrDA uses the Infrared Link Access Protocol (IrLAP), an adaptation of HDLC, as its data link protocol - the Infrared Link Management Protocol (IrLMP) is also used to provide a mechanism for handshaking and multiplexing of two or more different data streams simultaneously
IRDA port Infra-red Data Association port - a wire-less method of high-speed, line of sight, data transmission over short range
ISA Bus Industry Standard Architecture - this is a 'standard' expansion interface as used on PC compatibles (also referred to as the AT bus?)
ISDN Integrated Services Digital Network - a high speed network available in most European countries and the USA/Canada - it combines voice and data transfer through a single medium
ISO International Standards Organisation - they validate Pascal
ISP Internet Service Provider

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