B
- background
- The part of a glyph bitmap that surrounds the pixels that constitute the glyph itself
See also: foreground
- background color
- (1) The color that QuickDraw applies to the background parts of a glyph; specified by the bkColor field of the current graphics port. (2) The color of the pixels wherever no drawing has taken place. By default, the background color is white. (3) The color of the area between the dots of a halftone.
- background pattern
- The pattern displayed in a graphics port when an area is erased or when pixels are scrolled out of it.
- background printing
- A feature supported by some printer drivers that allows the user to work with an application while documents are printing. These printer drivers send printing data to a spool file in the PrintMonitor Documents folder inside the System Folder.
- background process
- A process that isn't currently interacting with the user
See also: foreground process
- background task
- A process that runs concurrently with another process without being the primary focus of the user's attention. The background task is allocated a percentage of the total processor time to accomplish its tasks. Several background tasks can be active at the same time
See also: foreground task
- background-only application
- An application that does not have a user interface.
- backing store
- A repository"typically a file on a paging device such as a hard disk"for pages of code or data that aren't currently in physical memory.
- backing volume
- A portion of a storage device used for backing store.
- backing-store file
See: backing store
- badge
- A visual element in a movie's display that distinguishes a movie from a static image. The movie controller component supplied by Apple supports badges.
- bad block sparing
- The process of working around a bad block by removing it from the pool of available free blocks.
- bad parameter error
- A nonfatal QuickDraw GX error indicating that one or more function parameters are incorrect.
- bad reference error
- A QuickDraw GX error indicating that an invalid reference to a view or font device, view group, or view port was made.
- balloon definition function
- An implementation of a window definition function that defines the general appearance of a help balloon
See also: help balloon
- band
- A horizontal strip from an image. The Image Compression Manager may break an image into bands if a compressor or decompressor component cannot handle an entire image at once.
- banner
- In a dialog box, an application-defined static text field that provides a specific prompt to the user.
- baseline
- An imaginary horizontal line that coincides with the bottom of each character in a font, excluding descenders (tails on letters such as p).
- baseline delta
- An array of distances (in points) between the various baseline types and y = 0
See also: baseline type
- baseline pitch
See: speech pitch
- baseline type
- The classification of baseline used with a particular kind of text. See, for example, Roman baseline.
- base family
- A group of closely related color spaces, across which color conversion can take place without the use of color profiles. RGB and HSV color spaces, for example, are all in the RGB base family.
- base frequency
- The pitch at which a sampled sound is recorded. The wave of a sampled sound may include frequencies other than the base frequency (and need not even include the base frequency).
- base media handler component
- A component that handles most of the duties that must be performed by all media handlers
See also: derived media handler component
- base register
- The register that holds a reference address used to access a fragment's data area.
- basic graphics port
- The drawing environment provided by basic QuickDraw. A basic graphics port is defined by a data structure of type GrafPort and contains the information that basic QuickDraw uses to create and manipulate onscreen either black-and-white images or color images that employ the eight-color system.
- basic QuickDraw
- The set of QuickDraw routines that you use to create and manipulate graphics information in a graphics port. All Macintosh computers have basic QuickDraw routines in ROM
See also: Color QuickDraw
- baud
- A measure of the bit sampling rate of a serial communication device.
- bcc recipient
- A 'blind courtesy copy' recipient of a letter. Bcc recipients are not listed in copies of the letter received by To and cc recipients
See also: original recipient
- best-effort delivery
- The level of reliability for the data delivery services that a connectionless protocol offers. The network attempts to deliver packets that meet certain requirements, such as containing a valid destination address, but it does not inform the sender when it is unable to deliver the packet; nor does it attempt to recover from error conditions and packet loss.
- bevel button
- A control that resembles a square, beveled push button. It can take the behavior of other controls, such as radio buttons, checkboxes, push buttons, and pop-up menu buttons.
- Bezier curve
- A curve, used for defining character shapes in outline fonts, defined by three outline points: two on-curve points that serve as endpoints and one off-curve point that determines the degree of curvature.
- bias
- (1) A number added to the binary exponent of a floating-point number so that the exponent field will always be positive. The bias is subtracted when the floating-point value is evaluated. (2) The number of bits to the right of a binary point in a fixed point number
See also: gxColorValue, fixed-point number
- bidirectional script system
- A script system where text is generally right-aligned with most characters written from right to left, but with some left-to-right text as well. Arabic and Hebrew are bidirectional script systems.
- binade
- The collection of numbers that lie between two successive powers of 2.
- binary floating-point number
- A collection of bits representing a sign, an exponent, and a significand. Its numerical value, if any, is the signed product of the significand and 2 raised to the power of the exponent.
- bind
- To find the referent of an import and place its address in a fragment's table of contents.
- bit
- The atomic memory unit. Each bit can be either set (the value of the bit is 1) or cleared (the value of the bit is 0).
- bitmap
- (1) A data structure of type BitMap that represents the positions and states of a corresponding set of pixels, which can be either black and white or the eight predefined colors provided by basic QuickDraw. A bitmap is contained within a basic graphics port
- bitmapped font
- A font made up of bitmapped glyphs
See also: outline font
- bitmapped glyph
- A bitmap of a character designed for display at a fixed point size for a particular display device.
- bitmap color profile
- The object that specifies color-matching information about the device on which a bitmap was created.
- bitmap color set
- An array of color values associated with a bitmap. If a bitmap uses a color set (as opposed to a color space), each pixel value in the bitmap's pixel image represents an index into this color set.
- bitmap color space
- A color space associated with a bitmap. If a bitmap uses a color space (as opposed to a color set), each pixel value in the bitmap's pixel image represents a color value in this color space.
- bitmap height
- The number of pixels in each column of a bitmap.
- bitmap position
- The position of the upper-left corner of a bitmap in geometry space.
- bitmap shape
- A type of QuickDraw GX shape. The geometry of a bitmap shape contains a pixel image and color information.
- bitmap structure
- A data structure that describes a pixel image.
- bitmap width
- The number of pixels in each row of a bitmap.
- bitmap/sequence number
- An ATP header field that is 8 bits long, the use and significance of which depend on whether the ATP packet is a request packet or a response packet. For request packets, this is the transaction bitmap; for response packets, this is the ATP sequence number.
- bit image
- A collection of bits in memory that forms a grid"that is, a rectangular pattern of bits. The bit image is pointed to in the baseAddr field of a BitMap record
See also: pixel image
- bit pattern
- An 8-by-8 pixel image drawn by default in black and white, although any two colors can be used on a color screen. A bit pattern can be repeated indefinitely to form a repeating design (such as stripes) when drawing lines and shapes or when filling areas on the screen
See also: pixel pattern
- bit-bucketing
- The practice of throwing away excess data when a SCSI target tries to supply more data than the initiator expects. Also includes sending meaningless data when a target requests more data than the initiator is prepared to supply. Both of these situations are abnormal and cause the SCSI Manager to return an error result code.
- black generation
- In CMYK color calculation, the substitution of black ink for areas with high intensities of cyan, magenta, and yellow
See also: undercolor removal
- black level
- The degree of blackness in an image. This is a common setting on a video digitizer. The highest setting will produce an all-black image whereas the lowest setting will yield very little, if any, black even with black objects in the scene. Black level is an important digitization setting since it can be adjusted so that there is little or no noise in an image.
- blank access privileges
- The directory access privileges under which a directory has the same access privileges as the directory's parent.
- blend matte
- A pixel map that defines the blending of video and digital data for a video digitizer component. The value of each pixel in the pixel map governs the relative intensity of the video data for the corresponding pixel in the result image.
- blend mode
- A transfer mode type in which the result is the average of the source and destination color components, weighted by a ratio specified by the operand component.
- blind transfer
- A Macintosh-specific method of transferring data between memory and the SCSI controller hardware, in which the SCSI Manager assumes that the SCSI controller (and the target device) can keep up with a specified transfer rate
See also: polled transfer
- block
- A group regarded as a unit; usually refers to data or memory in which data is stored
See also: allocation block, memory block
- block contents
- The area that's available for use in a memory block.
- block creator
- A four-character sequence that indicates which application created a message block; analogous to a file's creator in HFS.
- block device
- A device that reads or writes blocks of bytes as a group. Disk drives, for example, can read and write blocks of 512 bytes or more
See also: character device
- block header
- The internal housekeeping information maintained by the Memory Manager at the beginning of each block in a heap zone.
- block type
- A code that indicates the format of the data contained within a message block.
- board sResource
- A unique sResource in an expansion card's declaration ROM that describes the card so that the Slot Manager can identify it. An expansion card can have only one board sResource. The board sResource entries include the card's identification number, board flags, vendor information, initialization code, and so on.
- bomb box
See: system error alert box
- Boolean transfer mode
- (1) A specification of which Boolean operation QuickDraw should perform when drawing or copying an image into a bitmap or pixel map. Boolean transfer modes that draw patterns are called pattern modes; Boolean transfer modes that copy images or draw text are called source modes. (See also arithmetic transfer mode.) (2) Transfer mode types in which the result color is achieved by using Boolean operations on the bits of the source and destination color-component values.
- boot blocks
- The first two logical blocks on every Macintosh volume. Boot blocks contain instructions and information necessary to start up (or 'boot') a Macintosh computer
See also: system startup information
- Bopomofo
- Chinese phonetic characters. Also called Zhuyinfuhao.
- bottomline input
- A type of input method in which the user enters text in a small window, called a floating input window, that appears near the bottom of the screen.
- bottom-side bearing
- The white space between the bottom of the glyph and the visible ending of the glyph.
- boundary objects
- The elements, specified in a range descriptor record, that identify the beginning and end of the range
See also: range descriptor record
- boundary rectangle
- (1) A rectangle (by default, the entire main screen) that links the local coordinate system of a graphics port to QuickDraw's global coordinate system and defines the area of the pixel image or bit image into which QuickDraw can draw. The boundary rectangle is stored in either the pixel map or the bitmap. (2) The smallest rectangle that encloses a shape. The coordinates of a bounding rectangle are ordered.
- bounding box
- The smallest rectangle that entirely encloses the pixels or outline of a glyph.
- bounding rectangle
- A rectangle used to define other shapes, such as ovals and rounded rectangles. The lines of bounding rectangles completely enclose the shapes they bound; in other words, no pixels from these shapes lie outside the infinitely thin lines of the bounding rectangles.
- branch island
- A small assembly-language module used to transmit calls between two independently compiled modules. Branch islands are generated by the ILink linker to allow intrasegment calls to reach beyond 32 KB.
- brightness
- A term in color theory used to describe differences in the intensity of light reflected from or transmitted by a color image. The hue of an object may be blue, but the adjectives dark or light distinguish the brightness of one object from another
- browser list
- A list box that displays file objects for navigation and selection.
- browsing access
- The file access permissions that allow users to read but not modify a file.
- brush
- An abstract specification of a color or pattern. The system automatically sets a given brush type to the color or pattern that is appropriate for the current theme.
- buffered expansion
- Audio expansion of a sound that does not occur while the sound is playing
See also: real-time expansion
- bundle bit
- A flag in a file's Finder information record that informs the Finder that a bundle ('BNDL') resource exists for the file. A file's Finder information record is stored in a volume's catalog file. The Finder uses the information in the bundle resource to associate icons with the file.
- bundle resource
- (1) A resource of type 'BNDL' that is used by the Finder to associate an application and its files and icons. (2) A script system's international bundle resource.
- bus
- A path along which information is transmitted electronically within a computer. Buses connect computer devices, such as processors, expansion cards, and memory.
- bus free phase
- The phase in which no device is actively using the SCSI bus.
- bus interface
- The electronics connecting the processor bus to the NuBus expansion interface in Macintosh computers.
- bus sizing
See: dynamic bus sizing
- button
See: push button, radio button
- byte
- A bit quantity, used to store 28, or 256, different possible values. In the MC680x0 bit-numbering scheme, the first bit in a byte is bit number 7, and the last bit is bit number 0
See also: reversed bit-numbering
- bytes per row
- The number of bytes in a pixel image required to represent each row of a bitmap.
- byte lane
- Any of 4 bytes that make up the 32-bit NuBus data width. NuBus expansion cards may use any or all of the byte lanes to communicate with each other or with the Macintosh computer.
- byte offset
- (1) The indexed position of a byte in a text buffer, starting at zero for the first byte. In 1-byte script systems, byte offset is the same as character offset, and sequential values for byte offset correspond to the storage order of the characters. In 2-byte script systems, byte offset and character offset are different. (2) The numbering of character codes in source text
See also: edge offset
- byte smearing
- The ability of certain members of the 680x0 family of microprocessors to duplicate byte- and word-sized data across all 32 bits of the data bus.
- B*-tree
- (1) A method of organizing information into a collection of nodes. The nodes are arranged in a way that allows efficient access to the stored information. (2) A data structure used by the Dictionary Manager to organize dictionary index entries for fast searching.
- B*-tree control block
- A block of memory that contains information about a B*-tree file (either a catalog file or an extents overflow file).
- B*-tree file
- A file that is organized as a B*-tree
See also: catalog file, extents overflow file
- B*-tree header record
- A record in a header node that contains information about the beginning of the tree, as well as the size of the tree.