Text File | 1989-03-21 | 110.2 KB | 1,539 lines | [04] ASCII Text (0x0000)
Glossary Q-R
Quagmire register: On the Apple IIgs, the name given to the eight bits consisting of the speed control bit and the shadowing bits. Although Quagmire is not a real register, the Monitor program allows you to access those bits as if they were in a single register.
queue: A list in which entries are added at one end and removed at the other, causing entries to be removed in first-in, first-out (FIFO) order. Compare stack.
QuickDraw: The part of the Toolbox that performs all graphic operations on the Macintosh screen.
quit return stack: A stack maintained in memory by ProDOS 16. It contains a list of programs that have terminated but are scheduled to return when the presently executing program is finished.
quoting mechanism: Special syntax in the command line that tells the shell to interpret metacharacters literally, or to control the type of substitution allowed in the command.
QWERTY keyboard: The standard layout of keys on a typewriter keyboard; named for the first six letters on the top row of letter keys. Compare Dvorak keyboard.
radio-frequency (RF) modulator: A device that makes your television set work as a monitor.
radix: The number of digits in a number system; synonymous with base. For example, the base-10 system we commonly use has ten digits (0 through 9); thus, the radix is 10.
radix point: The symbol that separates the integer and fractional parts of a real number. In the base-10 system, the symbol is called the decimal point; in the base-2 system, the binary point.
RAM: See random-access memory.
RAM cache: Random-access memory you can designate to store certain information an application uses repeatedly. Using the RAM cache can greatly speed up your work, but may need to be used sparingly or not at all with applications that require large amounts of memory. You set the RAM cache in the Control Panel.
RAM disk: (1) A memory expansion card, used as a temporary storage area for data. Like a disk, it must be formatted with a particular disk operating system to store data. Unlike a disk, it acts like the random-access memory inside the computer, so that any data or program you put on the RAM disk can be read and used almost immediately, without making you wait while data comes in from a disk in an external disk drive. (2) A portion of RAM that appears to the operating system to be a disk volume. Files in a RAM disk can be accessed much faster than the same files on a disk. See also ROM disk.
random-access device: See block device.
random-access memory (RAM): The part of the computer's memory that stores information temporarily while you're working on it. A computer with 512K RAM has 512 kilobytes of memory available to the user. Information in RAM can be referred to in an arbitrary or random order, hence the term random-access. (As an analogy, a book is a random-access storage device in that it can be opened and read at any point.) RAM can contain both application programs and your own information. Information in RAM is temporary, gone forever if you switch the power off without saving it on a disk or other storage medium. An exception is the battery RAM, which stores settings such as the time and which is powered by a battery. (Technically, the read-only memory (ROM) is also random access, and what's called RAM should correctly be termed read-write memory.) Compare read-only memory.
random-access text file: A text file that is partitioned into an unlimited number of uniform-length compartments called records. When you open a random-access text file for the first time, you must specify its record length. No record is placed in the file until written to. Each record can be individually read from or written to-hence, random-access. Compare sequential-access text file.
raster: The pattern of parallel lines making up the image on a video display screen. The image is produced by controlling the brightness of successive points on the individual lines of the raster.
raw I/O: Data transferred directly between a device and user address space. Raw I/O bypasses kernel buffers, resulting in faster data transfer.
raw mode: A method of device driver operation that passes data between a terminal and a process without performing any conversions on the data. Compare cooked mode.
RDKEY: The firmware routine that a program uses to read a single keystroke from the keyboard.
read: To transfer information into the computer's memory from a source outside the computer (such as a disk drive or modem) or into the computer's processor from a source external to the processor (such as the keyboard or main memory).
Read Me document: A plain text document that is included on application and system software disks and provides you with late-breaking information about the product. You'll usually find Read Me documents in the Update Folder on the disk.
read-only memory (ROM): Memory whose contents can be read but not changed; used for storing firmware. Information is placed into read-only memory once, during manufacture. It remains there permanently, even when the computer's power is turned off. Compare random-access memory.
read-write head: The mechanism in a disk drive that reads data from a disk or writes information to it.
read-write memory: Memory whose contents can be both read and changed (or written to). The information contained in read-write memory is erased when the computer's power is turned off and is permanently lost unless it has been saved on a disk or other storage device. Used synonymously with random-access memory. Compare read-only memory.
read/write permission: Information associated with an access path that indicates whether the file can be read from, written to, or both read from and written to.
reallocate: To allocate new space in the heap for a purged block, updating its master pointer to point to its new location.
real number: In computer usage, a number that may include a fractional part; represented inside the computer in floating-point notation. Because a real number is of infinite precision, this representation is usually approximate. Compare integer.
real user ID: One of two user IDs associated by the kernel with a process. The real user ID identifies the user who is responsible for the process. Compare effective user ID. See also user ID.
Recent: In HyperCard, a special dialog box that holds pictorial representations of the last 42 unique cards viewed. Choose Recent from the Go menu to get the dialog box.
recharge routine: The function that supplies data to the output device when background printing is taking place.
record: (1) All the information about one person or one thing in a database. (2) A unit of storage in a random-access text file. Every random-access text file can contain a large number of records; each record holds the same number of characters. A program specifies a file's record length (in bytes) when the file is first opened; it must subsequently read and write to specific records within the file. (3) A component of an object module format (OMF) segment. All OMF file segments are composed of records, some of which are program code and some of which contain cross-reference or relocation information. Each record begins with an operation code that indicates the type of information to follow.
record length: The length of a random-access text file's records, in bytes. The maximum record length is 65,535 bytes in a 16-bit addressable system with all memory free; the minimum is 1 byte.
recursion: The continued repeating of an operation or a group of operations. A recursive procedure or function is one that, while running, calls itself. See also indirect recursion.
redirection: A feature of the shell that allows you to pass the output of a command to a file or device instead of to the terminal screen, and to supply a command with input from a file or device instead of from the keyboard.
Reduce or Enlarge: An option in the Page Setup dialog box (File menu) that lets you reduce or enlarge the print on a page, as many copying machines do.
reentrant: (adj.) Describes a routine that is able to accept a call while one or more previous calls to it are pending, without invalidating the previous calls. Under certain conditions, the Scheduler manages execution of programs that are not reentrant.
reference: (n.) The name of a segment or entry point to a segment; same as symbolic reference. (v.) To refer to a symbolic reference or to use one in an expression or as an address.
region: An arbitrary area or set of areas on the QuickDraw coordinate plane. The outline of a region should be one or more closed loops.
register: A memory location of a specific size in which each bit (or byte, depending on the size and design of the register) has some meaning to a microprocessor, program, or "smart" IC. IC registers are sometimes internal to the IC.
register-based routine: A Toolbox or Operating System routine that receives its parameters and returns its results, if any, in registers.
registered user: A user who has been given a user name and password by the AppleShare administrator.
regular expression: A notation that uses a special set of metacharacters for specifying a text pattern. For example, the vi and ex editors use the caret (^) metacharacter at the beginning of a regular expression to stand for the beginning of a line; therefore, the regular expression ^A stands for the set of all lines that begin with an uppercase A.
regular text: In HyperCard, text you type inside a field. You use the Browse tool to set an insertion point in a field and then type. Regular text is editable and searchable, whereas Paint text is not.
relational operator: An operator, such as > (greater than), that operates on numeric values to produce a logical result. Compare arithmetic operator, Boolean operator.
relative pathname: The name of a file, given by listing the directories leading to that file in relation to the current working directory. Directories common to both the working directory and the file are not included in the relative pathname. Compare absolute pathname.
release: When using an AppleShare print server, to remove a printer from a print server's control so that documents can be printed directly. Opposite of capture.
released: For an active-low signal, synonymous with high, inactive, deasserted, unasserted, and false.
release lever: The lever on the front of the LaserWriter's upper unit that you unlatch to open the LaserWriter.
relocatable: Characteristic of a load segment or other OMF program code that includes no references to specific address and so can be relocated at load time. A relocatable segment can be static, dynamic, or position independent. It consists of a code image followed by a relocation dictionary. Compare absolute.
relocatable block: A block that can be moved within the heap during compaction.
relocate: To modify an OMF file or segment at load time so that it will execute correctly at its current memory location. Relocation consists of patching the proper values onto address operands. The loader relocates load segments when it loads them into memory. See also relocatable.
relocation dictionary: In object module format, a portion of a load segment that contains relocation information necessary to modify the memory image portion of the segment. See also relocate.
RELOC record: A part of a relocation dictionary that contains relocation information for local (within-segment) references.
remote: (adj.) At a distance. Unable to be connected directly using wires only, but requiring communications devices. Compare local.
remote computer: A computer other than your own but in communication with yours through telephone lines or other communication links. A remote computer can be at any distance from your computer, from right beside it to thousands of miles away.
remote system: On a network, any computer other than the local system.
report: A subset of the information in a database. You may have a database with information about your employees-like their names, addresses, phone numbers, birthdays, social security numbers, and salaries. There are times when you want only a list of names and salaries-that's one report. Other times you want names and phone numbers-that's another report. You can generate all sorts of different reports from one database.
representative area: A small portion of the image that you can use to test changes to any settings. You can display the new results on the screen or print them.
reserved word: A word or sequence of characters reserved by a programming language for some special use and therefore unavailable as a variable name in a program.
reset: To restore all the default settings for a device with one action or command. The ImageWriter LQ can be reset by turning it off and back on (hardware reset) or by sending it an Esc C command (software reset).
Reset key: A key, labeled "Reset" or marked with a triangular symbol, whose function varies depending on the application you're using. On the Macintosh II, you can press Reset in combination with Control and Command to restart an application.
resident: (adj.) Present on; connected to. See disk-resident, memory-resident.
resolution: The degree of clarity of your display. A monitor has better resolution than a television set used as a monitor. Resolution is usually specified in dots per inch (dpi). The higher the value, the finer the detail of the image.
resolve: To find the segment and offset in a segment at which a symbolic reference is defined. When the linker resolves a reference, it creates an entry in a relocation dictionary that allows the loader to relocate the reference at load time.
resource: (1) A file contained in the System Folder that provides information the microprocessor needs to communicate with certain devices attached to the computer system. A printing resource is a system file that lets you print on a corresponding printer attached to the computer. (2) Data or code stored in a resource file and managed by the Resource Manager. Synonymous with driver.
resource attribute: One of several characteristics, specified by bits in a resource reference, that determine how the resource should be dealt with.
resource compiler: A program that creates resources from a textual description. The MPW Resource Compiler is named Rez.
resource data: In a resource file, the data that makes up a resource.
resource description file: In MPW, a text file that can be read by the Resource Compiler and compiled into a resource file. The Resource Decompiler disassembles a resource file, producing a resource description file as output.
resource file: Common usage for the resource fork of a Macintosh file.
resource fork: The part of a file that contains data used by an application, such as menus, fonts, and icons. An executable file's code is also stored in the resource fork. Sometimes called a resource file.
resource header: At the beginning of a resource file, data that gives the offsets to and lengths of the resource data and resource map.
resource ID: A number that, together with the resource type, identifies a resource in a resource file. Every resource has an ID number.
Resource Manager: A Macintosh tool for editing data in program segments without recompiling them.
resource map: In a resource file, data that is read into memory when the file is opened and that, given a resource specification, leads to the corresponding resource data.
resource name: A string that, together with the resource type, identifies a resource in a resource file. A resource may or may not have a name.
resource reference: In a resource map, an entry that identifies a resource and contains either an offset to its resource data in the resource file or a handle to the data if it's already been read into memory.
resource type: The type of a resource in a resource file, designated by a sequence of four characters (such as 'MENU' for a menu).
restart: To reactivate a dormant program in the computer's memory. The System Loader can restart dormant programs if all their static segments are still in memory. If any critical part of a dormant program has been purged by the Memory Manager, the program must be reloaded from disk instead of restarted. See also dormant.
restartable: Said of a program that reinitializes its variables and makes no assumptions about machine state each time it gains control. Only restartable programs can be resurrected from a dormant state in memory.
retrieval engine: See retrieval software.
retrieval software: Software designed to locate and display information on a CD-ROM.
return address: The point in a program to which control returns on completion of a subroutine or function.
Return key: A key that causes the cursor or insertion point to move to the beginning of the next line. It's also used in some cases to confirm a command.
RF modulator: See radio-frequency (RF) modulator.
RGB: Abbreviation for red-green-blue; a method of displaying color video by transmitting the three primary colors as three separate signals. There are two ways of using RGB with computers: TTL RGB, which allows the color signals to take on only a few discrete values; and analog RGB, which allows the color signals to take on any values between their upper and lower limits, for a wide range of colors.
RGB monitor: A type of color monitor that receives separate signals for each color (red, green, and blue). See also composite video.
ribbon cartridge deck: The platform inside the printer that holds the ribbon cartridge.
ribbon guide: The rectangle of plastic that rises over the print head. The ribbon travels between the ribbon guide and the paper guide.
rollers: The rollers inside the LaserWriter (under the green cover) that help in the process of fusing toner to paper. The rollers should be cleaned when the toner cartridge is changed.
ROM: See read-only memory.
ROM disk: A feature of some operating systems making it possible to use ROM as a disk volume. Often used for making applications permanently resident. See also RAM disk.
root: (1) Short for root directory. (2) Short for root user; the user with unlimited system privileges. Also called the superuser.
root directory: (1) The directory at the base of a file catalog. (2) The top directory in a UNIX directory hierarchy. Written as a slash ( / ), it is the first element in every absolute pathname.
root filename: The filename of an object file minus any filename extensions added by the assembler or compiler. For example, a program that consists of the object files MYPROG.ROOT, MYPROG.A, and MYPROG.B has the root filename MYPROG.
root file system: The file system that is always present on a UNIX system; the root file system can never be unmounted.
root user: See root.
routine: A part of a program that accomplishes some task subordinate to the overall task of the program.
routine selector: A value pushed on the stack to select a particular routine from a group of routines called by a single trap macro.
row: A horizontal arrangement of character cells or graphics pixels on the screen. Compare column.
row width: The number of bytes in each row of a bit image.
RS-232: A common standard for serial data communication interfaces.
RS-232 cable: Any cable that is wired in accordance with the RS-232 standard.
RS-422: A standard for serial data communication interfaces, different from the RS-232 standard in its electrical characteristics and in its use of differential pairs for data signals. The serial ports on the Apple IIgs use RS-422 devices modified so as to be compatible with RS-232 devices.
ruler: In MacWrite, Microsoft Word, and other word processing programs, a graphic representation of a ruler on which you set the format for the document, such as right and left margins, line spacing, and tabs.
run: (1) To execute a program. When a program runs, the computer performs the instructions. (2) To load a program into main memory from a peripheral storage medium, such as a disk, and execute it.
RUN: An Applesoft BASIC command that clears the current BASIC program and variables from memory, brings a BASIC program into memory from a file, and runs it. You can specify the starting point by indicating the first program line to be run.
run-time library file: A load file containing program segments-each of which can be used in any number of programs-that the System Loader loads dynamically when they are needed.
Glossary S-Sk
sampled sound synthesizer: A synthesizer (functionally equivalent to the Sound Driver's free-form synthesizer) that can play prerecorded or application-generated sounds.
sample edge: The falling edge (high to low) of the central system clock.
SANE: See Standard Apple Numerics Environment.
sans serif: Without serifs; serifs are fine lines that finish off the main strokes of a letter-like the little "feet" on the bottom of the vertical strokes in the letter M (Garamond). Avant Garde is a sans-serif font; the Avant Garde M looks like this: M.
sapling file: An organizational form of a ProDOS 16 standard file. A sapling file consists of a single index block and up to 256 data blocks. See also data block, index block, standard file. Compare tree file.
save: To store information by transferring it from main memory to a disk. Work not saved disappears when you switch off the computer or when the power is interrupted.
SAVE: An Applesoft BASIC command that lets you save the BASIC program currently in memory as a BASIC program file.
scaling factor: A value, given as a fraction, that specifies the amount a character should be stretched or shrunk before it's drawn.
scanner: Any graphic input device that converts printed matter into bit (digital) data.
scanning order: The order in which the operating system scans the disk drives looking for a startup disk.
scatter graph: A graph in which data are depicted as points in a two-dimensional field.
SCC: Abbreviation for Serial Communications Controller; a type of communications IC used in the Apple IIgs. An SCC can do the same things as an ACIA, but it also supports synchronous data transmission protocol and thus can transmit data at faster rates. An SCC handles serial I/O through the modem and printer ports.
SCCS: See Source Code Control System.
Scheduler: A firmware program that manages requests to execute interrupted software that is not reentrant. If, for example, an interrupt handler needs to make ProDOS 16 calls, it must do so through the Scheduler because ProDOS 16 is not reentrant. Applications need not use the Scheduler because ProDOS 16 is not in an interrupted state when it processes applications' system calls.
scientific notation: A method of expressing numbers in terms of powers of 10, useful for expressing very small or very large numbers. For example, 6.02E23, means 6.02 times 10 to the 23rd power. (The E stands for exponent.) The number is easier to understand in this form than in the form 602000000000000000000000. Applesoft BASIC uses this method to display real (floating-point) numbers with more than nine digits.
scrambled: Coded, to avoid detection.
scrap: A place where cut or copied data is stored.
Scrapbook: A desk accessory in which you can save frequently used pictures or passages of text.
scrap file: The file containing the desk scrap (usually the Clipboard).
Scrap Manager: The part of the Toolbox that enables cutting and pasting between applications, desk accessories, or an application and a desk accessory.
scratch: Disk space not normally available in the Macintosh operating system, but requested by some programs-Macintosh and non-Macintosh-for use as temporary storage.
screen: The part of the monitor where information is displayed. Like a movie screen, it's the place where things are projected. Also called the display screen.
screen buffer: A block of memory from which the video display reads the information to be displayed.
screen editor: A utility for entering and manipulating text. A screen editor displays the contents of a file by a full screen at a time. The commands to add or change text are entered anywhere on the screen, and the screen changes immediately to reflect the changes. The vi utility, for example, is a screen editor. Compare line editor.
screen font: A bit-mapped font intended for use on the computer screen. Compare internal font, printer font.
screen holes: Locations in the text display buffer (text Page 1) used for temporary storage either by I/O routines running in peripheral-card ROM or by firmware routines addressed as if they were in card ROM. Text Page 1 occupies memory from $0400 to $07FF; the screen holes are locations in that area that are neither displayed nor modified by the display firmware.
screen keypad: A feature of FT/TSO and FT/CMS used to duplicate 3278 function keys on the Macintosh.
screen shot: A MacPaint document that is like a snapshot of your Macintosh screen. You make a screen shot by holding down the Command and Shift keys and pressing 3.
script: (1) A writing system, such as Cyrillic or Arabic. The English language uses Roman script. (2) In HyperCard, a series of commands written in HyperTalk and associated with a particular object (such as a button, a field, a card, or a stack). (3) A file containing commands. See also shell script. (4) In MacroMaker, a recorded sequence of characters and commands, part of a macro.
script interface system: Special software that supports the display and manipulation of a particular script.
screen fonts: The fonts you see on the Macintosh screen, of which the LaserWriter has equivalent built-in fonts.
scroll: (1) To move a document or directory in its window so that a different part of it is visible. (2) To move all the text on the screen upward or downward, and in some cases sideways.
scroll arrow: An arrow at either end of a scroll bar. Clicking a scroll arrow moves a document or directory one line. Pressing a scroll arrow moves a document continuously.
scroll bar: A rectangular bar that may be along the right or bottom of a window. Clicking or dragging in the scroll bar causes your view of the document to change.
scroll box: The white box in a scroll bar. The position of the scroll box in the scroll bar indicates the position of what's in the window relative to the entire document.
SCSI: An acronym for Small Computer System Interface (pronounced "SKUH-zee"). An industry standard interface that provides high-speed access to peripheral devices.
SCSI cable terminator: A plug that absorbs the signals traveling along a SCSI cable, keeping the path open for new signals. If you have only one device, use one cable terminator. If you have two or more SCSI devices, put one cable terminator at the beginning and one at the end of the chain. Do not use more than two cable terminators.
SCSI chain: A group of SCSI devices linked to each other through SCSI peripheral interface cables and linked to the SCSI port on the computer through a SCSI system cable.
SCSI device access table (SDAT): A software table stored in the SCSI card RAM that contains a set of parameters for each SCSI device connected to the Apple II.
SCSI devices: Devices, such as hard disks and tape backup units, that use the Small Computer System Interface.
SCSI ID indicator: The small square hole on the back of an Apple SCSI device through which you can view the SCSI ID number as you change it with the SCSI ID switch.
SCSI ID number: (1) A number assigned to each SCSI device connected to a computer. The device with the highest number has priority if a conflict occurs while sending or receiving data. Some devices, such as internal hard disks, have preset SCSI ID numbers. On others, such as external hard disks, you use a SCSI ID switch to set the ID number. (2) The number assigned to a SCSI device based on the position of a hardware strap, jumper, or switch on the device itself. Compare unit number.
SCSI ID switch: The small hole below the SCSI ID indicator on the back of Apple SCSI devices. You insert a pushpin or straightened paper clip into the hole and press to change the SCSI ID number, shown on the indicator.
SCSI Manager: The part of the Macintosh Operating System that controls the exchange of information between a Macintosh and peripheral devices connected through the Small Computer Standard Interface (SCSI).
SCSI peripheral interface cable: The cable that links SCSI devices to each other. A peripheral interface cable has a 50-pin connector at each end.
SCSI port: The port on the back panel of the computer to which you connect SCSI devices.
SCSI system cable: The cable that links the first SCSI device with the computer. The system cable has a 50-pin connector at one end and a 25-pin connector at the other, which attaches to the computer.
search path: The route the computer must follow to retrieve a file you ask for.
search system: Same as retrieval software.
SE Bus: A direct data path to the microprocessor, implemented through a 96-pin expansion connector inside the Macintosh SE. Expansion cards for the SE Bus include accelerator cards and coprocessor cards.
SE Bus access port: An insert on the back panel of the Macintosh SE that allows access to the SE Bus expansion connector inside the computer. Used only for cables that run between an expansion card and a peripheral device.
secondary memory: Data and program storage for a computer. Secondary memory stores its information on physical media such as disk or tape. Secondary memory offers slower access time to data than main memory but provides more capacity. Compare main memory.
secondary shell prompt: A character displayed by the Bourne or Korn shell when the shell expects further input from you. This character is set by default to be the greater-than sign (>); the prompt appears, for example, when you use a multiline construct at the initial shell prompt. The secondary shell prompt reappears on each line until the final delimiter or the interrupt character is entered.
sector: (1) Part of a track on a disk; when a disk is formatted, its recording surface is divided into tracks and sectors. See also DOS 3.3, DOS 3.2. (2) Disk space composed of 512 consecutive bytes of standard information and 12 bytes of file tags.
seed: A value used to begin a repeatable sequence of pseudorandom numbers.
seedling file: An organizational form of a ProDOS 16 standard file. A seedling file consists of a single data block.
See Files: The AppleShare file server access privilege that gives the right to open and copy documents and applications in a folder.
See Folders: The AppleShare file server access privilege that gives the right to see folders within a folder.
segment: (1) One of several parts into which the code of an application may be divided. Not all segments need to be in memory at the same time. (2) A component of an OMF file, consisting of a header and a body. In object files, each segment incorporates one or more subroutines. In load files, each segment incorporates one or more object segments.
segment body: The part of a segment that follows the segment header and that contains the program code, data, and relocation information for the segment.
segment header: The first part of a program segment, containing such information as the segment name and the length of the segment.
segment kind: A numerical designation used to classify a segment in object module format. It is the value of the KIND field in the segment's header.
Segment Loader: The part of the Operating System that loads the code of an application into memory, either as a single unit or divided into dynamically loaded segments.
segment number: A number corresponding to the relative position of the segment in a file, starting with 1.
select: (v.) To designate where the next action will take place. To select using a mouse, you click an icon or drag across information. In some applications, you can select items in menus by typing a letter or number at a prompt, by using a combination keypress, or by using arrow keys. (n.) A command to a device such as a printer to place it into a condition to receive data.
Select button: A button on a printer that determines whether the printer should accept data from the computer or instructions from other buttons on the printer control panel (such as the line-feed button or form-feed button).
selection: (1) The information or items that will be affected by the next command. The selection is usually highlighted. (2) A series of characters, or a character position, at which the next editing operation will occur. Selected characters in the active window are inversely highlighted. Also called selection range.
Select light: A light on the control panel of the ImageWriter printer that indicates that the printer can receive data from a computer. None of the other control panel buttons work when the Select light is on. When the Select light is off, all buttons work, but the printer cannot print.
select switch: The switch on the AppleFax modem's front panel that lets you select either the AppleFax modem or an extra piece of equipment that's connected to the modem.
SE logic unit (SELU): See BBU.
semaphores: A group of system calls that allow processes to synchronize execution.
separation belt: In the LaserWriter, a small, clear plastic belt, located toward the back of the inside of the printer. When it breaks or is improperly installed, paper jams in the printer.
sequence symbol: In APW Assembler source files, a special kind of comment line that is not printed in the listing. These symbols are used by conditional assembly directives as branching destinations. The format consists of a period (.) followed by a label (the label may not contain any symbolic
parameters).
sequential-access device: See character device.
sequential-access text file: A text file made up of a sequence of fields. A field is a string of characters terminated by a return character. Sequential text files are best used for types of data that will be stored and retrieved sequentially. Compare random-access text file.
serial communication: Data communicated over a single-path communication line, one bit at a time.
Serial Communications Controller: See SCC.
serial data: Data communicated over a single-path communication line, one bit at a time.
Serial Driver: A device driver that controls communication, via serial ports, between applications and serial peripheral devices.
serial interface: An interface in which information is transmitted sequentially, one bit at a time, over a single wire or channel. Compare parallel interface.
serial interface cable: The cable that connects the serial ports of two devices, such as those of a computer and a printer. See serial interface.
serial interface socket: The ImageWriter LQ socket that accepts the serial interface cable's 8-pin mini-circular connector.
serial ports: The connectors on the back panel of the computer for devices that use a serial interface. See also modem port and printer port.
serial printer: A printer that accepts information from the computer by way of a serial interface.
serif: See sans serif.
server: A computer that provides a particular service across a network. The service may be file access, log-in access, file transfer, printing, and so on. Computers from which users initiate the service are called clients.
service request enable: A bit set by a device connected to the Apple Desktop Bus to tell the system that it needs servicing.
session: A series of transactions between two sockets, characterized by the orderly sequencing of requests and responses.
setup string: A group of characters that sends a format command to a printer. Some application programs, such as spreadsheets, give you the option of changing format, such as character width, by entering a setup string before printing.
setup time: The amount of time a signal must be valid in advance of some event. Compare hold time. See also valid signal.
shadowing: (1) The process by which any changes made to one part of the Apple IIgs memory are automatically and simultaneously copied into another part. When shadowing is on, information written to bank $00 or $01 is automatically copied into equivalent locations in bank $E0 or $E1. Likewise, any changes to bank $E0 or $E1 are immediately reflected in bank $00 or $01. (2) A process through which the SCSI card takes over an additional slot to work with ProDOS in supporting four external device ports.
shape definition: A coded description, consisting of one or more plotting vectors, of a shape to be drawn on a high-resolution graphics screen. See also plotting vector, shape table.
shape table: A collection of one or more shape definitions, together with their indexes.
shape table index: A list that gives the memory addresses of the shape definitions in a shape table.
shared memory: A mechanism that allows processes to share parts of their virtual address space.
shareware: Software you can copy and try before sending payment to the author.
shell: (1) A utility that accepts your commands, interprets them, and passes them on to the appropriate programs for execution. A/UX provides three shells: Bourne, C, and Korn. Each can be used as an interpreted programming language. Through shell variables and environment variables, you can tailor the environment of your shell for your own needs. (2) A program that provides an operating environment for other programs, and that is not removed from memory when those programs are running. For example, the APW Shell provides a command processor interface between the user and the other components of APW, and remains in memory when APW utility programs are running.
shell application: A type of program that is launched from a controlling program and runs under its control. Shell applications are ProDOS 16 file type $B5. In APW, compilers and certain shell commands are shell applications that are launched from the APW Shell.
shell call: A request from a program to the APW Shell to perform a specific function.
shell-call block: A set of instructions and directives used to make a shell call from an assembly-language program.
shell command: See built-in shell command.
shell layer: An instance of a shell, invoked by the shl program. Through this program, you can simultaneously run up to seven shell layers.
shell load file: A load file designed to be run under a shell program.
shell program: A series of commands to be executed by the shell. A shell program may be entered at the shell prompt or stored in a file. Shell programs that are stored in a file are referred to as shell scripts.
shell prompt: A character or string of characters displayed on the terminal to show that the shell is waiting for input from the user. The Bourne and Korn shells, for example, are set by default to display the dollar sign ($) as their prompts; the C shell is set by default to display the percent sign (%) as its prompt.
shell script: A shell program contained in a text file. Entering the name of the shell script from the command line executes the commands listed in the script.
shell variable: A variable local to the shell. A shell variable is available only to the current invocation of the shell, not to any of its subshells or spawned processes. Compare environment variable.
shielded cable: A cable with a special metallic wrapping around its wires. This wrapping reduces radio-frequency interference.
Shift-click: A technique that allows you to extend or shorten a selection by positioning the pointer at the end of what you want to select and holding down the Shift key while clicking the mouse button.
Shift-drag: A technique that allows you to select multiple objects by holding down the Shift key while you drag diagonally to enclose the objects in a rectangle.
Shift key: A key that, when pressed, causes the subsequent letter you type to appear in uppercase or the top symbol on a two-character key to be produced. The Shift key can also modify mouse actions. See Shift-click, Shift-drag.
short: In C, a 16-bit integer data type whose range is -32,768 to 32,767.
short name: A valid MS-DOS (or PC-DOS) filename that a server creates for every Macintosh or ProDOS volume name, folder name, or filename on the AppleShare file server.
shutdown: The temporary closing of a file server so it's not available on the network.
signal: A software interrupt that causes a program to be temporarily diverted from its normal execution sequence. A/UX uses both System V and BSD signals. Signals can be issued, handled, and otherwise manipulated via a set of system calls.
signal catcher: A function that detects the interrupt sent from a signal system call. See also signal.
signal handler: A function that performs the required processing upon receipt of a signal. See also signal.
single-sheet alignment icon: An icon on the single-sheet guide for aligning the left paper edge.
single-sheet guide: A movable plastic piece in the rear panel of the printer, used for loading single-sheet paper.
single-sheet paper: Any standard-sized paper that is unconnected to other sheets. Compare fanfold paper.
signature: A four-character sequence that uniquely identifies an application to the Finder.
significand: In scientific notation, the number that is acted upon by the exponent to yield the final value of the number. For example, in 6.02E23, 6.02 is the significand. See also exponent, scientific notation.
silicon (Si): A solid, crystalline chemical element from which integrated circuits are made. Silicon is a semiconductor; that is, it conducts electricity better than an insulator, but not as well as a metallic conductor. Silicon should not be confused with silica (silicon dioxide, such as quartz, opal, or sand) or with silicone (any of a group of organic compounds containing silicon).
SIMM: An acronym for Single In-line Memory Module; a circuit board that contains eight RAM chips. SIMMs attach to SIMM sockets on the computer's main circuit board.
Simplified Keyboard: See Dvorak keyboard.
simulation: A computerized representation of some process in action; for example, a flight simulation.
68000: The microprocessor used in the Macintosh, Macintosh Plus, and Macintosh SE. The 68000 has 32-bit data and address registers.
68020: The microprocessor in the Macintosh II. The Motorola 68020 can also be added to the Macintosh SE by means of an accelerator card installed in the SE Bus expansion connector.
68851: An optional coprocessor available for the Macintosh II that allows paged memory management, a technique that lets the microprocessor access a much larger body of data than can fit in RAM at one time. Sometimes referred to as the Paged Memory Management Unit, or PMMU.
68881: A coprocessor that provides high-speed support for processing scientific computations. Sometimes referred to as the floating-point unit, or FPU.
6502: The microprocessor used in the Apple II, the Apple II Plus, and early models of the Apple IIe. The 6502 is a MOS device with 8-bit data registers and 16-bit address registers.
65C02: A CMOS verson of the 6502; the microprocessor used in the Apple IIc and Apple IIe.
65C816: The microprocessor used in the Apple IIgs. The 65C816 is a CMOS device with 16-bit data registers and 24-bit address registers.
64K Apple II: Any standard Apple II that has at least 64K of RAM. That includes the Apple IIc, the Apple IIe, and an Apple II or Apple II Plus with 48K of RAM and the language card installed.
size box: A box in the lower-right corner of some active windows. Dragging the size box resizes the window.
Glossary Sl-Ss
slave: A card that responds to being addressed by another card acting as a master. The Macintosh II main logic board is a card that may be either master or slave. Some cards may be slave-only in function because they lack the circuitry to arbitrate in a bus ownership contest.
slide-show option: A feature of some applications that lets you arrange displays in a sequence so you can use them in presentations. The application changes "slides" after a certain time interval or when you press a certain key.
slop: See justification gap.
slot: A narrow socket inside some models of Apple computers for connecting circuit boards known as interface cards; each card handles communication between the computer and a peripheral device, sending and receiving data through a port or connector on the outside of the computer.
slot exec parameter block: A data structure that provides communication with the Slot Manager routines sMacBoot and sPrimaryInit.
slot ID: The hexadecimal number ($9 through $E in the Macintosh II) corresponding to each card slot. Each slot ID is established by the backplane (the main logic board of the Macintosh II) and communicated to the card through the /IDx lines.
Slot Manager: A set of Macintosh II ROM routines that let applications access declaration ROMs on slot cards.
slot number: A way an application might ask you to describe the location of a peripheral device. In some models of the Apple II, there are seven general-purpose slots on the main circuit board for connecting peripheral devices to the computer. They are numbered from 1 to 7 with 1 on the left as you face the front of the computer. If your device is connected to a port instead of a slot, you can still use the application by typing the slot number that corresponds to the port.
slot parameter block: A data structure that provides communication with all Slot Manager routines except sMacBoot and sPrimaryInit.
slot resource: A software structure in the declaration ROM of a slot card. Not to be confused with a resource.
slot space: NuBus address space $F900 0000 through $FEFF FFFF. It is divided into six regions, allocated for use by cards in the six Macintosh II slots. The upper 1/16th of each card's allocation is addressable by the Macintosh II in 24-bit mode.
Small Computer System Interface (SCSI): A specification of mechanical, electrical, and functional standards for connecting peripheral devices such as certain kinds of hard disks, printers, and optical disks to small computers.
SmartPort: A set of firmware routines supporting multiple block devices connected to the Apple IIgs disk port. See also extended SmartPort call, standard SmartPort call.
SNA/SDLC: Abbreviation for Systems Network Architecture/Synchronous Data Link Control. SNA is a set of rules for controlling the transfer of information in a data communication network. SDLC is a protocol that uses commands to control data transfer over a communication line. IBM telecommunications products manufactured after 1978 use this protocol. Compare binary synchronous communication.
socket: On a network, a communication mechanism originally implemented on the BSD version of the UNIX operating system. Sockets are used as endpoints for sending and receiving data between computers.
soft switch: A means of changing some feature of the computer from within a program. For example, DIP switch settings on ImageWriter printers can be overridden with soft switches. Specifically, a soft switch is a location in memory that produces some special effect whenever its contents are read or written. Also called a software switch.
software: A collective term for programs, the instructions that tell the computer what to do. Software is usually stored on disks. Compare firmware, hardware.
software overrun error: The condition that occurs when an input driver's buffer becomes full.
software pirate: A person who copies applications without the permission of the author. To copy software without permission is illegal.
software reset: The act of resetting the ImageWriter LQ printer to its default settings by sending the printer an Esc C command. A software reset does not clear any data in the print buffer. Compare hardware reset.
solenoid: A coil used as an electromagnet. In the BusinessWriter printer, the paper bail is opened and closed by a solenoid.
Solid Apple key: A modifier key on Apple IIc and older Apple II-family keyboards, marked with a filled-in Apple symbol. On newer keyboards, the Option key replaces the Solid Apple key. Compare Open Apple key.
sound buffer: A block of memory from which the sound generator reads the information to create an audio waveform.
Sound Driver: The device driver that controls sound generation in an application. (Superseded by the Sound Manager on the Macintosh II.)
sound procedure: A procedure associated with an alert that will emit one of up to four sounds from the Macintosh's speaker. Its integer parameter ranges from 0 to 3 and specifies which sound.
source: (n.) The original volume. When you are making a copy of a file or a volume, the source volume is the volume you are copying from; the destination volume is the disk you're placing the copy on. (adj.) Describes files that are being copied or translated as well as the disk or folder containing source files.
source code: See source file.
Source Code Control System (SCCS): A collection of commands used to control changes to text files, such as source code and documentation. SCCS protects files by controlling access and update privileges, and by preventing more than one user at a time from updating a file; SCCS also maintains an audit trail of revisions.
source file: An ASCII file consisting of instructions written in a particular language, such as Pascal or assembly language. An assembler or compiler converts source files into object files.
source program: The form of a program given to a language translator, such as a compiler or an assembler, for conversion into another form; sometimes called source code. Compare object program.
source volume: The original volume, as opposed to the duplicate (destination) volume. When you are making a copy of a file or a volume, the source volume is the volume from which you are copying. Compare destination volume. See also volume.
Space bar: The long, unlabeled bar along the bottom of the keyboard that you press to generate a space character.
space character: A text character whose printed representation is a blank space. You generate the character when you press the Space bar.
space parity: A method of error checking in data transmission in which the most significant bit of every byte is set to 0. The receiving device checks for errors by looking for this value on each character. Compare even parity, MARK parity, odd parity.
sparse file: A variation of the organizational forms of ProDOS 16 standard files. A sparse file may be either a sapling file or a tree file; what makes it sparse is that its logical size (defined by its EOF) is greater than its actual size on disk. This occurs when one or more data blocks contain nothing but zeros. Those data blocks are considered to be part of the file, but they are not actually allocated on disk until nonzero data is written to them.
spawn: To create and execute a new process with the fork and exec system calls.
special file: See device file.
special memory: On an Apple IIgs, all of banks $00 and $01, and all display memory in banks $E0 and $E1. So called because it is the memory directly accessed by standard Apple II programs running on the Apple IIgs.
spool: To send documents to the print server disk to be stored until they are printed. The word's origin is SPOOL, which stands for simultaneous peripheral operations on line.
spooler: See print spooler.
spool printing: (1) Writing a representation of a document's printed image to disk or to memory, and then printing it (as opposed to immediate draft printing). (2) The printing of bitmapped text in which the print manager writes QuickDraw commands to a file or to memory, and then the printer driver converts these commands into a bit image it sends as graphics data to the printer. Spool printing reproduces on paper the appearance of the characters on the screen. Compare draft printing.
spool programming: A programming technique that allows access to more information that can be stored in memory at one time. By storing on disk the majority of the image data, you need to have in memory only as much as you want to display. The rest of the picture data can be read into memory (spooled) from the disk and can replace the old displayed portion of the picture.
spreadsheet program: A type of application program that simplifies financial planning, cost estimating, and other number-crunching tasks. In a spreadsheet, information is laid out in columns and rows. Also called an electronic worksheet.
sprockets: The toothed wheels above or at the back of an ImageWriter printer that engage pin-feed paper and guide it through the machine.
square-wave synthesizer: The part of the Sound Driver used to produce less harmonic sounds than the four-tone synthesizer, such as beeps.
sResource: See slot resource.
sResource directory: The structure in a declaration ROM that provides access to its sResource lists.
sResource list: A list of characteristics of a slot resource.
SSC: Abbreviation for Super Serial Card; a peripheral card that enables an Apple II to communicate with serial devices.
Glossary St-Sz
stack: (1) In a computer, a portion of memory that is used for temporary storage of operating data during operation of a program. The data on the stack are added (pushed) and removed (pulled or popped) in last-in, first-out (LIFO) order. The stack usually refers to the particular stack pointed to by the 65C816's stack register. Compare queue. (2) A HyperCard document; a group of cards based on the same theme. See also card.
stack-based routine: A Toolbox or Operating System routine that receives its parameters and returns its results, if any, on the stack.
stack frame: The area of the stack used by a routine for its parameters, return address, local variables, and temporary storage.
stack register: A hardware register in the 65C816 processor that contains the address of the top of the processor's stack.
stand-alone computer: A computer that has its own disk drive and that can operate independently of the network.
Standard Apple Numerics Environment (SANE): The set of methods that provides the basis for floating-point calculations in Apple computers. SANE meets all requirements for extended-precision, floating-point arithmetic as prescribed by IEEE Standard 754 and ensures that all floating-point operations are performed consistently and return the most accurate results possible.
standard Apple II: Any computer in the Apple II family except the Apple IIgs. That includes the Apple II, the Apple II Plus, the Apple IIe, and the Apple IIc. See also 128K Apple II.
standard ASCII character: Synonymous with low ASCII character.
Standard C: A de facto standard definition of the C programming language, based on the most widely used implementation, the Berkeley VAX Portable C Compiler.
Standard C Library: A collection of routines for input and output, string manipulation, data conversion, memory management, and Integrated Environment support.
standard error output: The data stream used for error messages returned by a program. By default, the shell directs error output to your terminal screen. In APW C, synonymous with diagnostic output.
standard file: One of the two principal categories of ProDOS 16 files. Standard files contain whatever data they were created to hold; they have no predefined internal format. Compare directory file.
Standard File Package: A Macintosh package for presenting the standard user interface when a file is to be saved or opened.
standard input: The data stream used for input to a command. By default, the shell accepts as input the characters you type from your keyboard. The less-than sign (<) directs the shell to accept input from a file or device.
standard instruction: Synonymous with default.
standard output: The data stream used for output from a command. By default, the shell directs this to the terminal screen. The greater-than sign (>) directs the shell to write the output to a file or device.
standard-resolution graphics: For the ImageWriter LQ printer, graphics printed at a vertical resolution of 72 dots per inch, or 144 dots per inch for two-pass standard resolution graphics. Each dot column of standard-resolution graphics is represented by one byte of data. Compare high-resolution graphics.
standard SmartPort call: A SmartPort call that allows data transfer to or from anywhere in standard Apple II memory, or the lowest 64K of the Apple IIgs memory. Compare extended SmartPort call.
start bit: One or two bits that indicate the beginning of a character in a string of serially transmitted characters. Compare stop bit. See also data bits.
start cycle: The first period of a transaction during which /START is asserted. The start cycle is one bus clock period long; the address and transfer type are valid during this cycle.
starting value: The value assigned to the index variable on the first pass through a loop.
START13: An application on the DOS 3.3 System Master disk that makes it possible to run DOS 3.2-based applications.
start up: To get the system running. Starting up is the process of first reading an operating-system program from the disk and then running an application program. Synonymous with boot.
startup disk: A disk with all the necessary program files-such as the Finder and System files contained in the System Folder for the Macintosh-to set the computer into operation. Sometimes called a boot disk.
startup drive: The disk drive from which you started your application.
statement: A unit of a program in a high-level language that specifies an action for the computer to perform; it typically corresponds to several instructions of machine language.
static segment: A segment that is loaded only at program boot time and is not unloaded during execution. Compare dynamic segment.
status lights: Lights on the front of the LaserWriter printer that indicate the status of the printer-power on, paper jam, processing a job, and so on.
status line: The line on the Macintosh screen (located just below the host-data view area) used to display various symbols indicating the status of the host/Macintosh communications session.
status message: A message the LaserWriter sends to your computer when you confirm the Print command. The message may tell you the status of your job or alert you to a problem with the printer.
step value: The amount by which the index variable changes on each pass through a loop.
stepwise refinement: A technique of program development in which broad sections of the program are laid out first and then refined step by step until the program is complete.
sticky keys: An Easy Access feature that lets you type combination keystrokes without actually pressing the keys simultaneously. See also Easy Access.
stop bit: One or two bits that indicate the end of a character in a string of serially transmitted characters. Compare start bit. See also data bits.
storage type: An attribute of a ProDOS 16 file that describes the file's organizational form (such as directory file, seedling file, or sapling file).
store: See save.
stream: In C, a file with associated buffering.
stream editor: A utility for manipulating text. Rather than allowing you to move back and forth within a file interactively, a stream editor processes the text in a single pass. The sed utility, for example, is a stream editor. Compare interactive editor.
Streams: A collection of tools that assist programmers to modularize data transfer between device drivers and processes.
striker wire: A pin in the print head that strikes the ribbon to place a dot on the paper. The ImageWriter LQ print head contains a vertical column of 27 striker wires that are used to make columns of dots when printing characters and graphics.
string: An item of information consisting of a sequence of text characters (a character string) or a sequence of bits or bytes.
string option: A setting specified by a set of characters.
strobe: A signal whose change is used to trigger some action.
struct: In C, a record data type. Equivalent to record in Pascal.
structured language: A type of programming language in which programs are built out of smaller subprograms. Pascal is an example of a structured programming language.
style: See character style.
style dialog box: A dialog box that sets options affecting the page dimensions; associated with the Page Setup command.
subdirectory: A directory within a directory; a file (other than the volume directory or root directory) that contains the names and locations of other files. Every ProDOS 16 directory file is either a volume directory or a subdirectory. Equivalent to folder in some systems and applications.
subroutine: A part of a program that can be executed on request from another point in the program and that returns control, on completion, to the point of the request.
subscript: (1) An index number used to identify a particular element of an array. (2) A letter or number printed lower than the base line of the text that surrounds it. Compare superscript.
subshell: A new shell that is created from an existing shell; the subshell, or "child" shell, inherits the environment of its parent.
substring: A string that is part of another string.
superblock: The block following the boot block on every file system. The superblock contains the main information about the file system, such as its name, its size, and lists of the free blocks and free inodes.
super high-resolution mode: A graphics mode supported by the Apple IIgs that can display information using a rectangular array of 640 horizontal by 200 vertical dots in 4 colors or 320 horizontal by 200 vertical dots in 16 colors.
Super Hi-Res: Either of two high-resolution Apple IIgs display modes. One consists of an array of pixels 320 wide by 200 high, with 16 available colors; the other is an array 640 wide by 200 high, with 16 available colors (with restrictions).
SuperPILOT: An enhanced version of the original Apple II PILOT programming language. See also PILOT.
superscript: A letter or number printed higher than the base line of the text that surrounds it; for example, in the value 24, the 4 is a superscript. Compare
subscript.
superslot space: NuBus address space $9000 0000 through $EFFF FFFF. It is divided into six regions, allocated for intercard communication or other purposes by cards in the six Macintosh II slots.
superuser: See root.
supervisory program: A computer program whose primary function is scheduling, allocating, and controlling system resources, rather than processing information to get results. Compare application program, support program.
support program: A program that includes diagnostics, testing aids, data generation, terminal simulators, and so on. Support programs support the supervisory and application programs in a system. Compare application program, supervisory program.
suspend character: A character (by default, Control-Z under A/UX) that stops the foreground job and returns you to the shell. Entering the command fg brings the suspended job back to the foreground, where it resumes execution.
SVID: See System V Interface Definition.
swap space: A disk partition used for temporarily storing unneeded pages of code and data. See also page, paging.
switcher: A controlling program that rapidly transfers execution among several applications.
symbol: A character or string of characters that represents an address or numeric value; a symbolic reference or a variable.
symbolic parameter: In the APW Assembler, a variable character or character string that represents addresses or values declared in the prototype statement of a macro definition. There are three types of symbolic parameters: A (arithmetic), B (Boolean), and C (character). Symbolic parameters are assigned values by the SETA, SETB, or SETC directive.
symbolic reference: A name or label, such as the name of a subroutine, that is used to refer to a location in a program. When a program is linked, all symbolic references are resolved; when the program is loaded, actual memory addresses are patched into the program to replace the symbolic references.
symbol table: A table of symbolic references created by the linker when it links a program. The linker uses the symbol table to keep track of which symbols have been resolved. At the conclusion of a link, you can have the linker print out the symbol table.
synchronous: Able to perform two or more processes at the same time, such as sending and receiving data, by means of a mutual timing signal or clock. Compare asynchronous.
synchronous communication: See synchronous transmission.
synchronous execution: After calling a routine synchronously, an application cannot continue execution until the routine is completed.
synchronous modem: A modem that provides two clocks for synchronous communication with its host computer: one clock for sending data from the host computer to the modem, and a second clock for sending data from the modem to the host computer.
synchronous system: A system in which the sending and receiving units are operating continuously at substantially the same frequency.
synchronous transmission: A transmission process that uses a clocking signal to ensure an integral number of unit (time) intervals between any two characters. Compare asynchronous transmission.
syntax: (1) The rules governing the structure of statements or instructions in a programming language. (2) A representation of a command that specifies all the possible forms the command can take.
syntax error message: A message you get when the computer can't understand a command. The cause could be anything from mistyping a word to using a nonexistent command.
synthesizer: (1) A hardware device capable of creating sound digitally and converting it into an analog waveform that you can hear. (2) A program that interprets Sound Manager commands and produces sound. See also four-tone synthesizer, free-form synthesizer, square-wave synthesizer.
synthesizer buffer: A description of the sound to be generated by a synthesizer.
SYSOP: See system operator.
system: A coordinated collection of interrelated and interacting parts organized to perform some function or achieve some purpose-for example, a computer system comprising a processor, keyboard, monitor, and disk drive.
system cable: See SCSI system cable.
system call: Synonymous with operating-system call.
system configuration: See configuration.
system disk: A disk that contains the operating system and other system software needed to run applications.
system error alert: An alert box displayed by the System Error Handler.
system error alert table: A resource that determines the appearance and function of system error alerts.
System Error Handler: The part of the Operating System that assumes control when a fatal system error occurs.
system error ID: An ID number that appears in a system error alert to identify the error.
system event mask: A global event mask that controls which types of events get posted into the event queue.
System Failure Manager: A firmware program that processes fatal errors by displaying a message on the screen and halting execution.
system file: Any file the computer uses to start itself up or to provide systemwide information. Although system files are represented by icons just as documents and applications are, they can't be opened in the usual way. You can, however, alter the contents of system files. See also startup disk.
System file: A file Macintosh computers use to start up and to provide systemwide information. The System file contains system programs.
system file level: A number between $00 and $FF associated with each open ProDOS 16 file. Every time a file is opened, the current value of the system file level is assigned to it. If the system file level is changed (by a SET_LEVEL call), all subsequently opened files will have the new level assigned to them. By manipulating the system file level, a controlling program can easily close or flush files opened by its subprograms.
System V: The AT&T standard UNIX operating system. System V Release 2 forms the foundation of the A/UX system.
System V Interface Definition (SVID): AT&T's formal specification for compatibility with the UNIX operating system. A/UX adheres fully to the SVID.
system font: The font that the system uses (in menus, for example). In Roman-based writing systems, the system font is Chicago, and the system font size is 12 points.
system font size: The size of text drawn by the system in the system font; 12 points.
system heap: The portion of the heap reserved for use by the operating system.
System Loader: The program that manages the loading and relocation of load segments (programs) into the Apple IIgs memory. The System Loader works closely with ProDOS 16 and the Memory Manager.
system mailbox: A file in /usr/mail for holding your incoming electronic mail messages until you read them, at which time they are appended by default to the file mbox in your home directory and deleted from /usr/mail.
system operator (SYSOP): The human operator of a computerized bulletin board.
system program: (1) A program that makes the resources and capabilities of the computer available for general purposes, such as an operating system or a language translator. Compare application program, controlling program. (2) Under ProDOS 8, a stand-alone and potentially self-booting application. A ProDOS 8 system program is of file type $FF; if it is self-booting, its filename has the extension .SYSTEM.
system resource: A resource in the System Resource File.
System Resource File: A resource file containing standard resources, accessed if a requested resource wasn't found in any of the other resource files that were searched. Also called the System file.
system software: The component of a computer system that supports application programs by managing system resources such as memory and I/O devices.
system startup information: Certain configurable system parameters that are stored in the first two logical blocks of a volume and read in at system startup.
system window: A window in which a desk accessory is displayed.
Glossary T
tab: (1) Short for tabulator; on typewriter keyboards, a key that allows you set automatic stops (tab stops) or margins for columns, as in a table of figures. (2) An ASCII character that commands a device such as a printer to start printing at a preset location (a tab stop). There are two such characters: horizontal tab (hex 09) and vertical tab (hex 0B). The horizontal tab character gives the same action as pressing the tab key on a typewriter.
Tab key: A key that, when pressed, generates the horizontal tab character. The key's action is to move the insertion point or cursor to the next tab marker, or, in a dialog box with more than one place to enter information, to the next rectangle. The Tab key thus works essentially like a typewriter tab key.
tab marker: In MacWrite, an unfilled triangle under the inch scale of a ruler that marks the position to which the Tab key will move the insertion point. You get additional tabs by dragging them from the tab well.
tab well: In MacWrite, either of two boxes on the lower-left side of a ruler that hold regular and decimal tabs.
TCP/IP: Abbreviation for Transmission Control Protocol/Internet Protocol; a suite of networking protocols developed at the University of California for the U.S. Department of Defense.
TeachText: An application on the System Tools disk that lets you read plain text documents.
tear-off menu: Any menu that you can detach from the menu bar by pressing the menu title and dragging beyond the menu's edge. The torn-off menu appears in a window or a mini-window on the desktop. HyperCard has two tear-off menus: Tools and Patterns; once torn off they are called palettes.
telecommunication: Transmitting information across varying distances, such as over telephone lines.
telecommunications: The science and technology of communication by electrical or electronic means.
television set: A display device capable of receiving broadcast video signals (such as commercial television broadcasts) by means of an antenna; it can be used in combination with a radio-frequency modulator as a display device for the Apple II family of computers. Compare video monitor.
template: A predefined set of contents (numbers, text, and formulas) for a spreadsheet, designed for some specific purpose or task-for example, a budget template.
tenure: A time period of unbroken bus ownership by a single master. A master may lock the bus and, during one tenure, perform several transactions.
terminal: Synonymous with console.
terminal emulation window: The portion of the Macintosh screen used for host data and for the status line when in 3278 emulation mode.
terminal mode: The mode of operation in which the Apple IIgs acts like an intelligent terminal.
terminator: (1) A Setup menu option used to reset the AppleLine. (2) A device used in a SCSI chain to maintain the integrity of the signals passing along the SCSI chain. A SCSI chain should never have more than two terminators, one at each end of the chain. Also called a cable terminator.
test print: A printed page produced by the LaserWriter each time you switch it on.
text: (1) Information presented in the form of readable characters. (2) The display of characters on a display screen. Compare graphics.
text box: The place or places in any dialog box where you can type information.
TextEdit: The part of the Toolbox that supports the basic text entry and editing capabilities of a standard Macintosh application.
TextEdit scrap: The place where certain TextEdit routines store the characters most recently cut or copied from text.
text field: (HyperCard) See field.
text file: A file that contains information stored in the form of readable characters encoded using the ASCII format. On the Macintosh, they are known as Text Only documents. On the Apple II, they are called TXT files.
text file format: The Apple IIgs standard format for text files and program source files.
text generator: Firmware that prints characters on the screen in response to keypresses.
text mode: Information that is sent to the display in the form of characters that ft in a 40-column by 24-line grid or in an 80-column by 24-line grid. Compare graphics mode.
text property: A quality or attribute of a character's appearance. Properties include style, font, and size.
text window: (1) A window on the desktop within which text is displayed and scrolled. (2) The portion of the Apple II screen that is reserved for text. At startup, the firmware initializes the entire display to text. However, applications can restrict text to any rectangular portion of the display.
thermal printer: A printer that prints by heating small points that consequently produce colored dots on special heat-sensitive paper.
3.5-inch disk: A flexible, plastic disk measuring 3.5 inches in diameter and having a hard-shell plastic jacket. In spite of the hard cover, 3.5-inch disks are often called floppy disks as contrasted with hard disks. Two-sided 3.5-inch disks can store almost six times more data than single-sided 5.25-inch disks. Compare CD-ROM, 5.25-inch disk, hard disk.
three-state: A bus driver that drives a line low or high or doesn't drive it at all.
3x font: A font that is reduced in size from the font installed in a System file for high-density printed output. The Macintosh uses a ratio of 3:1 for ImageWriter LQ fonts.
threshold: The parameter that determines the level at which a gray shade is recorded as either black or white during a Line Art mode scan. A high value of the Threshold parameter results in a lighter overall image. A low value of the Threshold parameter results in a darker overall image.
thumb: The Control Manager's term for the scroll box (the indicator of a scroll bar).
tick: A 60th of a second.
tilde escape: The tilde character (~), used as an escape character to signal that the next input string is a command.
Time Manager: The part of the Macintosh Operating System that lets you schedule a routine to be executed after a given number of milliseconds have elapsed.
time sharing: Sharing a computer between two or more users, usually through multitasking.
title bar: The horizontal bar at the top of a window that shows the name of the window's contents. You can move the window by dragging the title bar.
TOF: See Top of Form.
toggle option: See toggle variable.
toggle variable: A setting for the shell environment that may be turned on or off with the set or unset command. For example, the set noclobber command entered from the C shell turns on a toggle variable that helps ensure existing files are not accidentally overwritten.
token: (1) An abbreviation of a string of characters. For example, Applesoft BASIC stores commands internally as single-character tokens. (2) A sequence of characters delimited so as to be identified by a compiler.
tool: (1) See toolbox, tool set. (2) An implement you use to do work. HyperCard has tools for browsing through cards and stacks, creating text fields, editing text, making buttons, and creating and editing pictures.
toolbox: A collection of built-in routines that programs can call to perform many commonly needed functions. Functions within the Apple IIgs Toolbox are grouped into tool sets. Compare User Interface Toolbox.
Toolbox Event Manager: The part of the Toolbox that allows your application program to monitor the user's actions with the mouse, keyboard, and keypad.
Toolbox Utilities: The part of the Toolbox that performs generally useful operations such as fixed-point arithmetic, string manipulation, and logical operations on bits.
tool set: A group of related routines (usually in firmware) that perform necessary functions or provide programming convenience. They are available to applications and system software. The Memory Manager, the System Loader, and QuickDraw II are Apple IIgs tool sets.
top margin: The distance from the top edge of a page to the first printed line of text.
Top of Form (TOF): The position of the print line relative to the top edge of the paper when you turn on the printer.
Top-of-Form command: A command causing a printer to feed paper until the paper advances to a preset position relative to the top of a single sheet.
traces: The electrical paths that connect the components on a circuit board.
tracks: A series of concentric circles that are magnetically drawn on the recording surface of a disk when it is formatted. Tracks are further divided into 8 to 12 consecutive sectors. A track corresponds to one ring of constant radius around the disk. See also DOS 3.3, DOS 3.2.
tractor: A belt with pins that guides pin-feed paper into the printer. The ImageWriter LQ has two tractors, one for each column of pin holes.
tractor release lever: A lever that, in the down position, locks its tractor into position. The up position frees the tractor for adjustment to a different paper width.
transaction: A complete NuBus operation such as read or write. In the Macintosh II, a transaction is made up of an address cycle, wait cycles as required by the responding card, and a data cycle. Address cycles are one clock period long and convey address and command information. Data cycles are also one clock period long and convey data and acknowledgement information.
Transcendental Functions package: A Macintosh package that contains trigonometric, logarithmic, exponential, and financial functions, as well as a random number generator.
transfer parameter: A characteristic of a file transfer type that can be modified for the file transfer process (for example, record size).
transfer type: The specific type of file being transferred as defined by the operating system or application program (for example, COBOL or MacBinary).
transistor-transistor logic (TTL): (1) A family of integrated circuits having bipolar circuit logic. TTLs are used in computers and related devices. (2) A standard for interconnecting such circuits, which defines the voltages used to represent logical 0s and 1s.
translate table: The table that controls character conversion between the Macintosh and the IBM host.
translation menu: A menu, such as "Mac to MS-DOS" or "Mac to Mac," that appears when two disks are shown in the Apple File Exchange window.
translator: The information that the Apple file exchange utility needs to translate a document created with an application on one operating system into a document that can be used with a similar application on another operating system.
translator file: A file containing one or more Apple File Exchange translators.
trap dispatcher: The part of the Operating System that examines a trap word to determine what operation it stands for, looks up the address of the corresponding routine in the trap dispatch table, and jumps to the routine.
trap dispatch table: A table in RAM containing the addresses of all Toolbox and Operating System routines in encoded form.
trap macro: A macro that assembles into a trap word, used for calling a Toolbox or Operating System routine from assembly language.
trap number: The identifying number of a Toolbox or Operating System routine; an index into the trap dispatch table.
trap word: An unimplemented instruction representing a call to a Toolbox or Operating System routine.
Trash: An icon on the desktop that you use to discard documents, folders, and applications.
tree file: An organizational form of a ProDOS 16 standard file. A tree file consists of a single master index block, up to 127 index blocks, and up to 32,512 data blocks. Compare sapling file. See also standard file.
tree structure: The layout of a UNIX directory hierarchy. Organized like an inverted tree, the directory hierarchy begins with the root directory at the top. Branching downward from the root are the rest of the directories and files in the system.
troubleshoot: To locate and correct an error or the cause of a problem or malfunction in hardware or software. When referring to software, synonymous with debug.
truncate: (1) To shorten by discarding a part. (2) To convert a real number to the next lower integer.
TTL: See transistor-transistor logic.
TTL RGB: A type of video monitor that can accept only a limited number of digital values and display only a correspondingly limited number of colors. Compare analog RGB.
tty: A terminal; abbreviated from teletypewriter, which was the first terminal device used on UNIX operating systems.
turnkey disk: See startup disk.
25-pin plug: A standard plug, having a maximum of 25 connector wires (pins), used to connect various devices to the computer. Standard plugs may have fewer than the maximum number of pins. They have an elongated shape like a flattened letter "D". Compare DIN connector.
2x font: Fonts that are twice the size (and therefore contain twice the amount of information about the shape of the image) as the fonts shown on your screen. Macintosh computers use 2x fonts when printing to an ImageWriter II in Best quality mode to create a higher-resolution image of each character.
type: (n.) Printed or typewritten characters. (v.) To produce characters by pressing keys on a keyboard.
type-ahead buffer: A buffer that accepts and holds characters that are typed faster than the computer can process them.
typehead: See print head.
Glossary U-Z
uid: See user ID.
umount: A system administration command that removes a local file system.
unary operator: An operator that applies to a single operand. For example, the minus sign (-) in a negative number such as -3 is a unary arithmetic operator. Compare binary operator.
unasserted: For an active-low signal, synonymous with high, deasserted, false, inactive, and released.
unbuffered: A buffer style that does not use a buffer for I/O; reading and writing is done one character at a time.
unconditional branch: A branch that does not depend on the truth of any condition. Compare conditional branch.
unidirectional printing: A mode of printer operation in which characters are printed only when the print head is moving from left to right. Compare bidirectional printing.
unimplemented instruction: An instruction word that doesn't correspond to any valid machine-language instruction but instead causes a trap.
unit number: A hexadecimal number assigned to a SCSI device by the firmware, based on the device's SCSI ID number. Compare SCSI ID number.
UNIX operating system: A general-purpose time-sharing system and related set of utilities, originally developed at AT&T Bell Laboratories. A/UX is an enhanced version of the UNIX operating system for the Macintosh II computer. UNIX is a registered trademark of AT&T Information Systems.
unlink: To remove a directory entry for a file.
unload: To remove a load segment from memory. To unload a segment, the System Loader does not actually "unload" anything; it calls the Memory Manager to either purge or dispose of the memory block in which the code segment resides. The loader then modifies the Memory Segment Table to reflect the fact that the segment is no longer in memory.
unlock: (1) To remove the restriction on the use of a disk or a file so that it can once again be changed, deleted, or renamed. Compare lock. (2) To allow a relocatable block to be moved during heap compaction.
unmount: To remove a file system from the directory hierarchy. Local file systems are unmounted with the umount command; remote file systems accessed via the Network File System are unmounted with the unmount command. Compare mount.
unmounted volume: A volume that hasn't been inserted into a disk drive and had descriptive information read from it, or a volume that previously was mounted and has since had the memory used by it released.
unmovable: See fixed.
unordered: In SANE, the result of a comparison between two NaNs, even identical ones. See also NaN.
unpurgeable: Having a purge level of 0. The Memory Manager is not permitted to purge memory blocks whose purge level is 0.
unpurgeable block: A relocatable block that can't be purged from the heap.
unsigned char: In C, an 8-bit character data type whose range is 0 to 255. Same as char.
unsigned int: In C, a 16-bit integer data type whose range is 0 to 65,535. Same as unsigned short.
unsigned long: In C, a 32-bit integer data type whose range is 0 to 4,294,967,295.
unsigned short: In C, a 16-bit integer data type whose range is 0 to 65,535. Same as unsigned int.
update event: An event generated by the Window Manager when a window's contents need to be redrawn.
Update Folder: A folder on the System Tools disk, and on other application and system disks, that contains Read Me documents.
update region: A window region consisting of all areas of the content region that have to be redrawn.
user: A person operating or controlling a computer system.
user group: A computer club in which computer users exchange tips and information, usually about a particular brand of computer.
user ID: (1) A number that identifes you as a subscriber to an information service. (2) In A/UX, a number that identifies a user at the time of login. Abbreviated uid.
User ID: An identification number that specifies the owner of every memory block allocated by the Memory Manager. User IDs are assigned by the User ID Manager.
User ID Manager: A tool set that is responsible for assigning User IDs to every block of memory allocated by the Memory Manager.
user interface: The rules and conventions by which a computer system communicates with the person operating it.
User Interface Toolbox: The software in the Macintosh ROM that helps you implement the standard Macintosh user interface in your application.
user level: The setting on the User Preferences card in the Home stack that lets you use HyperCard's tools and abilities. Five user levels are available: Browsing, Typing, Painting, Authoring, and Scripting.
user name: (1) A unique name assigned to a registered user and used to identify that user on the network. (2) See login name.
user prefix: The prefix of a fully qualified TSO filename designating the user ID of the file's owner.
utility: In general, an application program that performs a relatively simple function or set of functions. Examples are the Font/DA Mover and the Installer. An APW utility is a program that runs under the APW Shell and that performs a function not handled by the shell itself. MakeLib is an example of an APW utility.
valid partition: A device partition that has a Partition Descriptor Map created for it in the Device Partition Map.
valid signal: A signal whose voltage is a valid representation of the logic variable it portrays. See also hold time, setup time.
value: An item of information that can be stored in a variable, such as a number or a string.
variable: (1) A location in the computer's memory where a value can be stored. (2) The symbol used in a program to represent such a location. Compare constant.
VBL: Abbreviation for vertical blanking; an interrupt signal generated by the video timing circuit each time it finishes a vertical scan, 60 times a second.
VCB: See volume control block.
vector: (1) The starting address of a program segment, when used as a common point for transferring control from other programs. (2) A memory location used to hold a vector, or the address of such a location. (3) A location that contains a value that, when added to a base address value, yields the entry point address of a subroutine.
vector table: A table of interrupt vectors in low memory.
Versatile Interface Adapter (VIA): The I/O chip that handles the Apple Desktop Bus, real-time clock, and various other control signals and interrupts. In the Macintosh II, a second VIA handles control and interrupts for RAM, SCSI, and NuBus.
version: A number indicating the release edition of a particular piece of software. Version numbers for most system software (such as ProDOS 16 and the System Loader) are available through function calls.
version data: In an application's resource file, a resource that has the application's signature as its resource type; typically a string that gives the name, version number, and date of the application.
vertical retrace interrupt: An interrupt generated 60 times a second by the built-in Macintosh video circuitry while the beam of the display tube returns from the bottom of the screen to the top. (In the Macintosh II, a virtual vertical retrace interrupt is generated by the VIA.)
Vertical Retrace Manager: The part of the Operating System that schedules and executes tasks during the vertical retrace interrupt.
VIA: See Versatile Interface Adapter.
video: (1) A medium for transmitting information in the form of images to be displayed on the screen of a cathode-ray tube. (2) Information organized or transmitted in video form.
videodisc: A double-sided optical disc capable of storing and playing back full-motion video.
video driver: In the Macintosh II, the device driver that handles the interface between QuickDraw and a slot-based video device.
video monitor: A display device that can receive video signals by direct connection only and cannot receive broadcast signals such as commercial television; it can be connected directly to the computer. Compare television set.
viewport: All or part of the display screen used by an application program to display a portion of the information (such as a document, picture, or worksheet) on which a program is working. Compare window.
virtual memory: Memory space that is separate from the main memory (physical RAM) and is instead located in auxiliary memory media (usually disks). The ability of a system to address virtual memory space is important for multitasking operating systems and applications too large to be handled in RAM alone.
void: In C, a data type used to declare a function that does not return a value.
volume: A general term referring to a storage device or to part of a storage medium formatted to contain files; a source of or a destination for information. A volume can be an entire disk or only part of a disk. A volume has a name and a volume directory with the same name. Its information is organized into files.
volume attributes: Information contained on volumes and in memory indicating whether the volume is locked, whether it's busy (in memory only), and whether the volume control block matches the volume information (in memory only).
volume bitmap: A portion of every ProDOS 16-formatted disk that keeps track of free disk space.
volume control block (VCB): (1) A nonrelocatable block that contains volume-specific information, including the volume information from the master directory block. (2) A data structure set up in memory by ProDOS 16 to keep track of all volumes and devices connected to the computer.
volume directory: The main directory file of a volume. It contains the names and locations of other files on the volume, any of which may themselves be directory files (called subdirectories). The name of the volume directory is the name of the volume. The pathname of every file on the volume starts with the volume directory name. See also directory file, subdirectory.
volume name: (1) The name of the volume directory. (2) A sequence of up to 27 printing characters that identifies a volume; followed by a colon (:) in File Manager routine calls, to distinguish it from a filename. (3) The name of a disk or its main directory. Compare pathname.
warm start: The process of transferring control back to the operating system in response to a failure in an application program. Compare cold start.
Wastebasket: An icon shaped like a wastepaper basket in the AppleFax document window. Dragging an address or distribution list to the Wastebasket removes the address-book entry. Dragging an envelope to the Wastebasket deletes the envelope and removes it from the activity report.
waveform: The shape of a wave (a graph of a wave's amplitude over time).
waveform description: A sequence of bytes describing a waveform.
wavelength: The horizontal extent of one complete cycle of a wave.
wave-table synthesizer: Similar to the old four-tone synthesizer, the wave-table synthesizer produces complex sounds and multipart music.
wide area network: A system of interconnected local area networks that spans a wide geographical area.
wildcard character: A character that may be used as shorthand to represent a sequence of characters in a pathname. A common wildcard character is the asterisk (*). As an example, if you were to request a listing of *.TEXT files in a particular application, you would see a list of all files ending with the suffix TEXT. In APW, the equal sign (=) and the question mark (?) can be used as wildcard characters.
window: (1) The area that displays information on a desktop; you view a document through a window. You can open or close a window, move it around on the desktop, and sometimes change its size, scroll through it, and edit its contents. See also mini-window. (2) The portion of a collection of information (such as a document, picture, or worksheet) that is visible in a viewport on the display screen. Each window is internally represented in a window record. Compare viewport.
window class: In a window record, an indication of whether a window is a system window, a dialog or alert window, or a window created directly by the application.
window definition function: A function called by the Window Manager when it needs to perform certain type-dependent operations on a window (for example, drawing the window frame).
Window Manager: The part of the Toolbox that provides routines for creating and manipulating windows.
Window Manager port: A GrafPort that has the entire screen as its PortRect and is used by the Window Manager to draw window frames.
window template: A resource (type 'WIND') that contains information from which the Window Manager can create a window.
wire: See striker wire.
word: (1) The computer's native unit of data. The Macintosh II uses a 32-bit word. A NuBus word is 32 bits long; a half-word is 16 bits. An SE Bus or 68000 word is 16 bits long; a half-word is 8 bits. For the Apple IIgs, a word is 16 bits (2 bytes) long. (2) For the shell and other programs, a string of nonblank characters bounded by the space character, the tab character, or the beginning or the end of the input line.
word processor: A type of application program designed to make writing and editing easier and faster.
word search: See keyword search.
word-selection break table: A break table that is used to find word boundaries for word selection, spelling checking, and so on.
word wrap: The automatic continuation of text from the end of one line to the beginning of the next. Word wrap lets you avoid pressing the Return key at the end of each line as you type.
word-wrapping break table: A break table that is used to find word boundaries for screen wrapping of text.
working directory: See current directory.
workstation: (1) A Macintosh, Apple II, or IBM PC that you can use to do your work and send or receive information over a network. AppleShare workstations are connected to the AppleTalk network system. (2) An individual work area that includes one or more devices on a network. (3) A node through which a user can access a server or other nodes.
WORM: Acronym for write once, read many times. WORM is a type of optical drive that allows the user to save his own data to the disc once and access the information as often as he wants. This type of drive gives the user an economical way of storing archival information for repeated access.
wraparound: See word wrap.
wristwatch: The icon you see on the screen in place of the arrow pointer when the computer is performing an action that causes you to wait.
write: To transfer information from the computer to a destination external to the computer (such as a disk drive, printer, or modem) or from the computer's processor to a destination external to the processor (such as main memory).
write-enable notch: The square cutout on one edge of a 5.25-inch disk's jacket. If there is no write-enable notch, or if it is covered with a write-protect tab, the disk drive can read information from the disk but cannot write on it.
write-protect: To protect the information on a disk. You write-protect a 5.25-inch disk by covering the write-enable notch with a write-protect tab, preventing the disk drive from writing any new information onto the disk. You lock (write-protect) a 3.5-inch disk by sliding the small tab in the left corner on the back of the disk toward the disk's edge. Compare copy-protect, lock.
write-protect tab: (1) A small adhesive sticker used to write-protect a 5.25-inch disk by covering the write-enable notch. (2) The small plastic tab in the corner of a 3.5-inch disk jacket. You lock (write-protect) the disk by sliding the tab toward the edge of the disk; you unlock the disk by sliding the tab back so that it covers the rectangular hole.
x flag: One of three flag bits in the 65C816 processor that programs use to control the processor's operating modes. In native mode, the setting of the x flag determines whether the index registers are 8 bits wide or 16 bits wide. See also e flag, m flag.
x-height: The height of a lowercase "x" in a given font; the height, measured from the base line, of the main portion of most lowercase letters in a font, excluding ascenders and descenders. See also ascent line, base line, descent line.
XOFF: A special character (value $11) used for controlling the transfer of data between a DTE and a DCE. When one piece of equipment receives an XOFF character from the other, it stops transmitting characters until it receives an XON. See also handshaking, XON.
XON: A special character (value $13) used for controlling the transfer of data between a DTE and a DCE. See also handshaking, XOFF.
XON/XOFF: A communications protocol that tells the computer to start or stop sending data by sending the appropriate character: either an XON or an XOFF. The ImageWriter LQ sends an XOFF when its input buffer is nearly full and an XON when it has room for more data. Compare hardware handshake.
XOR: See exclusive OR.
X register: One of the two index registers in the 6502 microprocessor.
Yellow Pages: A Network File System protocol for sharing a common database of user information across a local area network.
Y register: One of the two index registers in the 6502 microprocessor.
zero page: The first page (256 bytes) of memory in a standard Apple II computer (or in the Apple IIgs when running a standard Apple II program); also called page zero. Because the high-order byte of any address in this page is zero, only the low-order byte is needed to specify a zero-page address. This makes zero-page locations more efficient to address, in both time and space, than locations in any other page of memory. Compare direct page.
zone: (1) One or more networks, collectively identified by a zone name, that are part of a larger, interconnected network. Users in a zone can easily share network services such as printers or servers. (2) A network in a series of interconnected networks, joined through bridges.
zone record: A data structure representing a heap zone.
zoom box: A small box with a smaller box enclosed in it found on the right side of the title bar of some windows. Clicking the zoom box expands the window to its maximum size; clicking it again returns the window to its original size.
A P P E N D I X
Creating a Glossary for Your Manual
A GOOD GLOSSARY CAN ENHANCE A MANUAL'S USEFULNESS TO READERS MUCH
as do the table of contents and a good index. Here are some guidelines for preparing a glossary.
v Note: Glossary, as used here, refers to an alphabetized list of terms with definitions-not the collections of keywords used in Microsoft Word for formatting a document.
Audience considerations
Keep in mind the needs of the people for whom you are writing. Follow the guidelines in this section.
Know your audience
If your manual is intended for first-time computer users or first-time Apple product users, you'll probably have to include terms you might think of as having obvious meanings-such as disk drive, 3.5-inch disk, System file, window, screen, menu, start up, and command. Earlier user manuals can serve as guides when deciding what to include; developmental editors can also make helpful suggestions.
Technical manuals needn't assume computer illiteracy on the part of readers-you may not have to define general computer terms like silicon or application program. However, you should probably assume that some readers will be ignorant of Apple terminology. Terms like language card, Finder, or IWM (Integrated Woz Machine) should probably be in the glossary if your manual uses them. Again, it depends on your audience; for example, the glossary of Inside Macintosh, Volumes I-III, does not include Finder but does include File Manager.
Intermediate manuals or installation manuals for peripheral devices lie in a gray area. Can you assume, for example, that the person buying a hard disk has already learned how to use the computer? Perhaps not. But some hard disk buyers will be highly advanced users. When deciding which terms to include, you should probably err on the side of including terms that most readers might already know, rather than leaving out those that some readers won't know, insofar as the terms belong in the manual's context.
Make definitions explanatory as well as correct
Give an example where appropriate; if possible, make that example specific to the system about which you're writing. Where helpful, refer to other glossary terms for further information or contrast.
Make the context clear
Is your definition general to all computers, specific to Apple computers, specific to a particular device or system, or somewhere in between? If a term has two or more meanings that are relelvant (such as format, the noun referring to page appearance, and format, the verb referring to the action performed on a blank disk), provide all definitions.
Connect ordinary usage with technical meaning
Many ordinary English words have specific meanings with regard to computer products. In manuals for first-time users, it's helpful to show the connection between the ordinary meaning of the word and its new, technical meaning. For example, here's the Apple Publications Glossary definition of open:
open: To make available. You open files or documents in order to work with them. A file may not be read from or written to until it is open. In the desktop interface, opening an icon causes a window with the contents of that icon to come into view. You may then perform further actions in the window when it's active.
The initial definition of open, "to make available," is one of the meanings given the verb in The American Heritage Dictionary. It provides a conceptual link to the reader.
Matters of form
These guidelines tell how entries should be formatted and structured and what conventions we follow in Apple manuals.
Galaxy Design
The current version, version 3.0, is in Galaxy Design using Microsoft Word 3.02. You may have to reformat entries that you paste into Grand Design, Nova Design, or other designs.
The Microsoft Word glossary macro sets up the entire Glossary section and page format for you, including the opening, footers, and division break. Once your glossary document is set up, you can type your own entries or cut and paste entries from the Apple Publications Glossary disk. See the design documentation for specs and sample pages.
Format of an entry
The term to be defined is in boldface, followed by a boldface colon and one plain space. Do not capitalize the term unless it is a proper noun.
The definition, in plain text, starts with a capital letter and ends with a period. The first clause of the definition is a sentence fragment. Other parallel phrases in the definition may also be sentence fragments; otherwise, use complete sentences.
Alphabetization
Alphabetize entries letter by letter up to a punctuation mark; spaces do not count. For example, controller comes before control panel. Numerical entries are ordered as though they were spelled out. For example, 6502 comes between shell and soft switch.
Where there are several similar numeric entries, however, such as 68000, 68020, 68851, and so on, order the entries numerically within the group. This is a change to the previous rule; Apple III now comes after Apple II.
Parts of speech
If the term is a verb, start the definition with an infinitive ("To make available") and not a gerund ("Making available"). If the term is an adjective, you may have to start the definition with wording such as "Said of . . . ," "Characteristic of . . . ," "Used to describe . . . ," or some such. You may also use (n.), (v.), or (adj.) for noun, verb, or adjective to distinguish the part of speech.
Pronunciation
When defining acronyms or other terms with unusual or unclear pronunciation, provide a key in this form:
ASCII: Acronym for American Standard Code for Information Interchange (pronounced "ASK-ee").
EBCDIC: Acronym for . . . (pronounced "EB-si-dik").
leading: Pronounced "LED-ing"; the amount of blank vertical space between. . . .
The pronunciation key is inside quotation marks; hyphens separate the syllables, and all-caps indicates the stress.
Cross-references
Within your definition, use boldface for other terms in the glossary that you want the reader to consult in relation to this definition. Use italics for terms that are synonyms or antonyms but that don't need to be looked up separately (or don't appear in your glossary). If you use a term that appears in the glossary but do not want to draw particular attention to it, just use roman (plain text). Avoid making entries look like this:
(Cluttered)
open: To make available. You open files or documents in order to work with them. A file may not be read from or written to until it is open. In the desktop interface, opening an icon causes a window with the contents of that icon to come into view. You may then perform further actions in the window when it's active.
If you think cross-referencing is needed, it's often better to do so this way, with cross-references at the end:
(Better)
open: To make available. You open files or documents in order to work with them. A file may not be read from or written to until it is open. In the desktop interface, opening an icon causes a window with the contents of that icon to come into view. You may then perform further actions in the window when it's active. Compare close. See also icon, window.
s Important
Make sure all cross-referenced terms are in your glossary. s
"See" means that the definition for a term is given elsewhere.
"See also" means that additional relevant information is given elsewhere.
"Compare" means that a contrasting or complementary term is defined elsewhere. It isn't necessary to say "Compare with. . . ." You may also use "Same as" and "Opposite of" for synonyms and antonyms.
Multiple definitions
Each definition in a sequence is preceded by a number in parentheses followed by a single space:
graphics: (1) Information presented in the form of. . . . (2) The display of pictures. . . .
If the definitions are for different parts of speech, each one is preceded by the part-of-speech abbreviation in parentheses with a period:
branch: (v.) To pass program control to a line or statement other than the next in sequence. (n.) A statement that performs the act of branching. See also conditional branch, unconditional branch.
More complexity is possible; consult your developmental editor, if necessary, when dealing with complex entries.
Independence
Your glossary should stand alone. Don't include references to text sections or to other publications.
Assembling the glossary
First, decide which terms you need to include and define for your readers.
Second, check specific glossaries for your group. The Networking and Communications Group and the technical writers working on the Apple IIgs books, for example, have assembled specialized glossaries with definitions that may not appear in the Apple Publications Glossary.
Third, look in the Apple Publications Glossary, and cut and paste any entries you want from the disk. Your Area Associate should have a copy of the disk files.
v By the way: It's not necessary to copy the entire Apple Publications Glossary into your document.
Fourth, check other Apple manuals for highly specific definitions that may not have been included in the specialized glossaries or general Apple Publications Glossary.
Finally, look in other dictionaries or write your own definition.
You don't necessarily have to use an existing definition verbatim. Make up your own variant or examples if appropriate. If an entry contains both a simple definition and a complex one, and you don't need both, pick out the part that is applicable. Feel free to correct errors or misconceptions if you find them, and please pass the correct information on to your developmental editor.
