## MMPM/2 Device Driver Reference

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### Glossary - B

B

background color - The color assigned to a background image.

background mix - An attribute that determines how the background of a graphic primitive is combined with the existing color of the graphics presentation space.

base device driver - An OS/2 device driver that performs I/O during the OS/ 2 kernel boot sequence to provide IPL support. Base device drivers are loaded by way of the CONFIG.SYS BASEDEV keyword, rather than the DEVICE keyword. See BASEDEV keyword, adapter device driver, and device manager.

BASEDEV keyword - New CONFIG.SYS keyword; loads a base device driver into the operating system.

Basic Input/Output System (BIOS) - Code that controls basic hardware operations, such as interactions with diskette drives, hard disk drives, and the keyboard.

Bezier curve - A mathematical technique of specifying a smooth, continuous line or surface, requiring a starting point and an ending point, with several intermediate points that influence or control the path of the linking curve.

BIOS - Basic Input/Output System.

bit-block transfer (bitblt) - Transfer of a rectangular array of bit-map data.

bitblt - Bit-block transfer.

bit map - A representation of an image by an array of bits.

block - (1) In programming languages, a compound statement that coincides with the scope of at least one of the declarations contained within it. A block may also specify storage allocation or segment programs for other purposes. (I) (2) A string of data elements recorded or transmitted as a unit. The elements may be characters, words or physical records. (T) (3) A collection of contiguous records recorded as a unit. Blocks are separated by interblock gaps and each block may contain one or more records. (A)

Bit block transfer (bitblt) - The process of transferring one or more blocks of data.

border - A visual indicator of a window's boundaries.

BPB - BIOS Parameter Block.

breakpoint - (1) A point in a computer program where execution may be halted. A breakpoint is usually at the beginning of an instruction where halts, caused by external intervention, are convenient for resuming execution. (T) (2) An instruction in a program for halting execution. Breakpoints are usually established at positions in a program where halts, caused by external intervention, are convenient for restarting. (T) (3) A place in a program, specified by a command or a condition, where the system halts execution and gives control to the workstation user or to a specified program.

Bus Master adapter - An adapter capable of performing Reads and Writes to physical storage by communicating directly with the storage subsystem ( memory) rather than depending on a host DMA channel or host CPU. Synonymous with first-party DMA adapter.