Appendix Glossary O

In the left margin you will find links to the glossary categorised alphabetically. Some of the pages are quite long and may take a few moments to load if you use a modem. This glossary is always being updated.

Glossary - O

Object - A graphical image such as a photograph visible on a display monitor, that may be manipulated using one or more components of a software application.

Object Oriented - In programming, a combination of code, which is a sequence of instructions referred to as functions, along with data units, referred to as structures. In the past, operating systems dealt with these entities separately. The combination of function and structure, called an object, allows for significant advantages to programmers as well as the end users of software.

OCR - (Optical Character Recognition) a type of system comprised of hardware and software that is capable of scanning text or images into a file with a user having the ability to edit the material. There is a great advantage to using OCR because when text is scanned using an ordinary optical scanner, the image is stored as a bitmap (in simple terms, one large picture). The OCR, on the other hand, allows the user the ability to edit the scanned text as though it were entered using a word processing program.

Odd Parity - Data integrity checking in which the parity bit checks for an odd number of 1s.

OEM Original equipment manufacturer. When seen in a computer ad (e.g., "Sound Blaster OEM"), this generally means a lower-cost product that does not come in a retail box, usually lacking in manuals, bundled software and other accessories.

Offline - Not connected, either to one of a computer's supportive hardware devices such as a printer or scanner, or to the Internet.

Offline Reader - Software that allows a user to log onto the Internet, download Web pages and email, and view them offline at the user's leisure.

OLE - (Object Linking and Embedding) software that allows a user to create a file in one application and incorporate it into another, while retaining the original file format and association to the program that created it. Windows and Macintosh operating systems allow for OLE.

On The Fly - A Web page with dynamic content, or one where the content is frequently changed. On the fly is the opposite of a static or hardwired page whose content seldom changes.

OnLine - This means that the computer is turned on and ready to compute!

Opcode - The data that represents a microprocessor instruction.

Open Transport - Macintosh networking protocol starting with Macintosh Operating System version 7.5.3.

Operating System - This is the piece of software on your computer which takes instructions from you, and does the task you desire. They also aid in organisation, and can play a big role in the speed of your computer. Examples of operating systems are Microsoft Windows, UNIX, Linux, Microsoft Windows 95, Microsoft Windows NT, DOS, MacOS, and many others.

Optical Disk - A data storage medium that utilises laser technology to read information. CD-ROMs and WORM (Write Once Read Many) are examples of optical disks.

Optical Scanner - Often simply called a scanner, a device that reads images and text, allowing a user to input and utilise the data in various applications. A scanner digitises the image. This means it divides the entire image into tiny boxes and assigns a value to each isolated unit using 0s and 1s. Essentially, this is what a bitmap is. The scanned image, whether text or a graphic, therefore, becomes a bitmap. Consequently, the scanned data cannot be directly altered unless optical character recognition technology is used.

Optimise - The term has several common uses. 1. to structure and arrange hardware devices for maximum efficiency. 2. to tune up a computer system, as in running defragmentation software and eliminating unwanted data to free up disk space. 3. to make adjustments to an operating system or software application so it runs more efficiently.

Option - An item typed after a DOS command that is not required for the running of the program. It is sometimes called a "switch" as it switches on additional instructions for the computer. A way to customise the running of a program.

Orphan - In word processing and publishing, the last line of a paragraph appearing on the first line of a page. Some applications adjust for this. Orphan is synonymous with widow.

OS - "Operating System" The OS is the base layer of a computing environment, upon which the application level software (or programs) can be run. Examples of popular operating systems are Macintosh, Windows, and UNIX. Without an operating system, a computer would be unable to work at all, and without application programs, a computer would work but be unable to perform any useful tasks.

OS2 - A Microsoft operating system developed in the 1980s that is compatible with DOS and Windows programs. OS2 applications however, will not run on Windows or DOS. Originally, the development of OS2 was a joint venture between IBM and Microsoft. It is now a sole product of IBM.

Output - Data resulting from the operation of a computer. Output may be displayed on a monitor, printed, stored on a disk, or played on loudspeakers.

Output Device - Any computer hardware that facilitates the interpretation of computer data. Display monitors, speakers and printers are output devices.

Overhead - Command overhead refers to the processing time required by the controller, host adapter, or drive prior to the execution of a command. Lower command overhead yields higher drive performance. Disk overhead refers to the space required for non- data information such as location and timing. Disk overhead often accounts for about ten percent of drive capacity. Lower disk overhead yields greater disk capacity.

Overwrite - To write data on top of existing data thus erasing it.