John Cletheroe's
PC And Internet Hints

PC And Internet Glossary - Including File Extensions - I

I/O Addresses

Input/Output Addresses. See that entry.

IANA

Internet Assigned Numbers Authority. The organisation responsible for assigning TCP and UDP port numbers (and possibly other functions). External link (unverified): http://www.iana.org

IC

Integrated circuit; chip.

ICANN

Internet Corporation for Assigned Names and Numbers. The body responsible for the creation of new top-level Internet domain names.

ICF

Internet Connection Firewall. The software firewall facility provided as part of Windows XP. Generally considered to be significantly inferior to even the free firewall programs such as Sygate and ZoneAlarm, but probably better than nothing.

ICMP

Internet Control Message Protocol. That part of the IP (Internet Protocol) that handles control and error messages.

ICO

File extension. Icon file. Contains the graphical image of the icon. Icons can also be stored in other types of file, particularly EXE and DLL files. I think icons can have various sizes. I do not know whether ICO files can contain viruses or not; it seems highly unlikely.

ICQ

"I seek you". A program which allows two (or more???) parties to hold a real-time conversation over the Internet (I think). Descriptions that I've seen tend to be extremely vague and do not make it clear whether this conversation (called "chat") is by means of text messages typed into the keyboard and displayed on the screen, or by speech (in which case a sound board, speakers and a microphone would be required by both parties, presumably). The program might even support input from a video camera. I think ICQ probably uses the IRC protocol. I get the impression that chat programs tend to be incompatible with each other.

Opinion: An excellent method of running up a huge telephone bill.

ICS

Internet Connection Sharing. A method of connecting several computers in the same building to the Internet. All the computers are connected via a LAN (local area network). One of the computers is also connected to the Internet, via a modem, ADSL, ISDN or cable modem, etc. I get the impression that ICS is provided with Windows 98SE and later but this may not be correct.

ID3

A tag associated with MP3 files which holds information such as the track's artist name and track title. I think ID3 tags are stored within MP3 files rather than being held as separate files.

IDE

Integrated Drive Electronics. A means of connecting peripherals inside a computer, especially hard disks. Extremely fast. A computer can have up to four IDE devices, attached to two ribbon cables. One ribbon cable connects to the Primary Master and Primary Slave devices, the other ribbon cable to the Secondary Master and Secondary Slave connections.
Integrated Development Environment. A program used to edit and compile programs in a programming language such as Visual BASIC.

IDEA

International Data Encryption Algorithm.

IDF

File extension. Outlook Express mail folder index file. I do not know whether IDF files can contain viruses or not; it seems unlikely.

IDS

Intruder Detection System. That part of a firewall program which should detect potentially malicious incoming Internet traffic.

IE

Microsoft Internet Explorer.

IEAK:

Microsoft KnowledgeBase article title prefix for articles relating to Internet Explorer Administration Kit.

IEEE 802.3

Ethernet.

IEEE 1394

See FireWire.

IF

Interactive Fiction. A sub-genre of computer adventure games, often text-only or with very limited graphics, and sometimes where puzzle-solving is secondary to story-telling.

IFO

File extension. DVD Info File.

IFRAME

Inline frame. Also called a floating frame. A web page inserted into another web page by means of the IFRAME tag. Unfortunately the IFRAME tag is not interpreted by Netscape Navigator V4 and therefore it should not be used in public Internet web pages. The word IFRAME is included in one of Internet Explorer V4's custom security options but with no explanation of the term.

IIRC

Often used in online discussions as a shorthand for "If I remember correctly...".

IIS

(Microsoft) Internet Information Services. Software which enables a computer to operate as a server on the Internet. There are many other similar products available some of which enjoy a far superior reputation than Microsoft's offerings. IIS has an atrocious record regarding security.

IKE

Internet Key Exchange. An obscure internal Internet protocol.

iLink

See FireWire.

IM

File extension. See this entry on my Trainz Wordz page.

IMAP

Internet Message Access Protocol. An email protocol, similar to POP3.

IME

Input Method Editor. A component of Windows XP.

IMEP

Microsoft Internet Email Enhancement Patch for Outlook 97. See Microsoft KnowledgeBase articles 167146 and 168782.

IMHO

In my humble opinion.

IMO

Internet Mail Only. A mode of Outlook 2000 (and possibly other versions of Outlook), the other mode being CW (Corporate Workgroup). I think the mode is chosen when the program is installed, and there may be a third "no email" option.

Indigo

The codename for a new communications sub-system which Microsoft intends to include in Longhorn (the new version of Windows, currently under development).

Indirection

The principle, widely used throughout computing, of operating on a pointer to data rather than the physical data itself. An example of indirection is the use of shortcuts in Windows 95 and later editions.

Indirection, while extremely useful, is always potentially extremely confusing for both the user and the programmer. It is very difficult for most users to know if they are operating on the data or the pointer to it. For example, many Windows users may delete a shortcut, thinking they are actually deleting its program. In Windows XP, Microsoft have added a comment explaining this when a shortcut is deleted. Similarly, many Windows users are very confused about the relationship between the Start button menu structure (an organised set of shortcuts which can be freely modified by the user) and the actual locations of program files (mostly in folders within C:\PROGRAM FILES but often also in individual top-level folders of C:\) which in most cases cannot be simply changed by the user. Another confusion can arise regarding whether a Start button entry, a Desktop shortcut, a Quick Launch Bar shortcut and an association through a data file extension will all run exactly the same program or different versions of the program which have been installed over a period of time, or the same version in different modes.

Whereas web browsers, word processing programs and spreadsheet programs represent data directly, database programs inevitably represent it indirectly. For example, a database program may be capable of displaying a file in different sequential orders, sorted by any of its key fields. It may also be capable of displaying views, which appear to the user to be files but which are actually combinations of fields from one or more files, often only including only some fields and some records from each file.

In my opinion indirection is the main reason why so many people have great difficulty understanding how computer software works. One example of this is the difficulty so many people have operating, designing and programming database programs and systems.

INF

"inf". File extension. Setup information file. For modems, the inf files is effectively a device driver. Having the correct modem information file for your exact modem model installed and selected is vital in order that the modem operates at the highest speed and with the best compression and error correction settings, and that the connection speed of each call is correctly interpreted and displayed by Windows. INF files can contain instructions which could perform undesirable operations on a computer.

Infoseek

A well known search engine.

http://www.infoseek.com

Inheritance

A term used in object oriented programming. The act of creating a new class based on an existing class, inheriting most of the behaviour of original class as a default basis for the behaviour of the new class. The alternative terms "extend", "derive" and "subclassing" have the same meaning.

INI

"in-eee". File extension. Initialisation File (so called because it is read when a program starts). Configuration settings file for older programs. More modern programs store their configuration settings in the Registry. I do not know whether INI files can contain viruses or not; it seems unlikely, but an INI file could well contain a malicious entry which causes an undesirable effect.

Input/Output Addresses

Also commonly I/O Addresses. Each peripheral device connected to a PC has one or more input/output addresses. These appear to the PC's processor as if they were normal memory addresses. The device can send its output on an input address, which the processor can read as if it were reading a memory location. The processor can write data to an output address, which is sensed as an incoming signal by the peripheral. Since each device must have a different set I/O addresses, in the past some devices, especially expansion boards, had DIP switches or jumpers which allowed their range of I/O addresses to be set. However, discovering a working combination of I/O settings was somewhat tricky for PC installers, and the selected range usually had to be specified in the software configuration. In an attempt to solve this problem the PnP (Plug and Play) system was developed. See also DMA and IRQ.

INS

File extension. MIDI Instrument Definition file. I do not know whether INS files can contain viruses or not; it seems unlikely.
File extension. Internet Naming Service.

Insert a disk labelled...

Insert a disk which contains a copy of the relevant programs, files, etc. The program wants to read these files.
Insert a blank disk. The program is about to write the relevant programs, files, etc to this disk. When this has been done you should eject the disk, write the appropriate wording on the disk's label and store it safely.

Unfortunately Microsoft use these two opposite meanings interchangeably, leading to much confusion. This is a good example of a short ambiguous phrase being used where a longer, less ambiguous phrase is required.

Insertion Point

The black flashing vertical line between two characters, which indicates where text will be inserted if you type. Also often called the text cursor and occasionally the caret.

Installation File(s)

The file or files required in order to install a program. For a program downloaded via the Internet the distribution file usually expands to form the installation file(s). Running the installation procedure (usually SETUP.EXE or INSTALL.EXE) creates the target files.

Instance

In operating systems such as Windows, which can have several programs loaded at the same time, it is under some circumstances possible to load more than one copy of the same program at the same time. Well written programs should warn the user when they attempt to load a second copy but sadly in practice very few programs do. Some programs automatically prevent more than one copy of themselves being loaded at the same time. Each copy of a program loaded at the same time is called an instance.
In object oriented programming, a class is a template from which individual copies of an object are created. Each operative copy of the object is called an instance. At design time object templates are often displayed in a toolbox. Once created, each instance is independent and can have different properties to the other copies of the same type of object. For example, each text box in a program can have a different size. he process of creating each copy is sometimes called "instantiation" - a truly revolting word. An instance of a class is called an object.

Internet Explorer

Microsoft's web browser program. Separate from and different to Windows Explorer. Separate from but closely associated with Microsoft's email program, Outlook Express.

Generally Internet Explorer is less reliable and much slower than Netscape Navigator and early versions of Opera. It does have the advantage of displaying the real source file in response to VIEW > SOURCE FILE, making it a very good choice if you use Notepad to create and edit your HTML files.

Sadly Internet Explorer has arcane internal version numbers which bear no resemblance to the external version numbers.

Interpreter

A program which runs a program written in a high level language. Unlike a compiler, an interpreter does not convert the program to machine code but instead effectively runs a series of machine code subroutines. Interpreters are far more convenient to use since there is no compilation process and diagnostic information such as the values of variables can be very easily obtained. However, interpreters tend to run programs more slowly than they would run if compiled.

Intranet

A private network which uses Internet transmission protocols.

Intro

See Demo [3].

IP

Internet Protocol. See TCP/IP.
Intellectual Property (as in copyright, etc).

IP Address

The physical address of a device connected to the Internet. IP addresses consist of four numbers each in the range 0 to 255, separated by full stops, for example 123.45.67.89. See also DNS.

IPF

Invalid Page Fault. A common type of error message in Windows.

IPP

Internet Printing Protocol. See Microsoft KnowledgeBase article 294439 for more information.

IPX

Internetwork Packet Exchange. A network protocol used Novell Netware networks instead of IP (Internet Protocol).

IRC

Internet Relay Chat. An Internet protocol which provides real-time text communication between two or more users. See also ICQ.

IRQ

Interrupt Request. PC's have a number of inputs from external devices, called Interrupt Requests. When an external device needs the processor's attention (for example, when it is ready to send or receive data) it sends a signal on its IRQ. The processor is then interrupted from its current task in order to service the device. Each device needs a different IRQ number, although for reasons I do not understand some devices can share a number. In the past each device had DIP switches or jumpers which allowed its IRQ to be set. However, there are a number of IRQ's which cannot be changed, for fundamental devices such as memory and the keyboard. Discovering a working combination of IRQ settings was a nightmare for PC installers. In an attempt to solve this problem the PnP (Plug and Play) system was developed. See also DMA and Input/Output Addresses.

ISA

Industry Standard Architecture. The type of expansion socket fitted on the original IBM PC, and expansion boards designed for that type of socket. Capable of handling 8-bit and 16-bit data. See also PCI and AGP.
Microsoft Internet Security And Acceleration.

ISAM

Indexed Sequential Access Method. A file accessing system which allows files to be read sequentially or randomly by any key field. For example, with ISAM a file containing surnames and telephone numbers can be read sequentially by surname or sequentially by telephone number and in addition any record can be accessed by specifying a surname or telephone number. ISAM files must have indexes, which can be stored along with the data or as separate files. The more indexes an ISAM file has the longer any file writing operations take. With ISAM the chronological sequence in which records are entered into the file is usually irrelevant.

ISAPI

(Microsoft) Internet Server Application Programming Interface.

ISDN

Integrated Services Digital Network. A digital telephone transmission system. Dial-up (not a permanent connection/leased line/private circuit). Requires a special modem-like device at each end. ISDN installation and call charges are not much more than for conventional analog phone lines in North America and mainland Europe but extremely expensive in Britain due to the BT monopoly. Maximum transmission speeds with ISDN are 128kbps, only about double those with an X2/K56Flex/V.90 modem.

ISO9660

One of several possible file name systems which can be used on CD's. ISO9660 filenames must conform to the MS-DOS 8+3 standard (a maximum of eight characters for the filename, a full stop [period] and a maximum of three characters for the extension [file type]). The only characters permitted are upper case letters, digits, the underline character and the one full stop between the filename and the extension. No spaces are allowed. There must be strictly one full stop. No other punctuation characters are allowed. ISO9660 CD's can be read by MS-DOS, Apple Mac, OS/2, Windows (all versions including NT), Unix and Linux. See also Joliet.

ISP

Internet Service Provider.
File extension. Internet Communication settings. ISP files can contain instructions which could perform undesirable operations on a computer.

ISS

File extension. A type of file used by the Inno Setup installation routine creation system.
Internet Security Systems. A software publishing company.
In other context: International Space Station.

Itanium

A 64-bit processor manufactured by Intel. The Pentium is a 32-bit processor. I don't know if the Itanium is yet on sale, whether it can be fitted in a conventional PC, or whether any software yet makes use of its extra facilities. According to some tests a Pentium processor executes 32-bit optimised programs faster than an Itanium processor running at the same clock speed.

ITC

Internet Transfer Control. A custom control for Visual BASIC which presumably provides FTP facilities. Supplied with the Professional and Enterprise editions of Visual BASIC V5 and V6. An alternative to directly using the WinInet API.

ITS

Internet Document Set.

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