Revision as of 14:18, 14 November 2017

By IBM

Reprint Courtesy of International Business Machines Corporation, © International Business Machines Corporation

This is the standard IBM SDK/DDK Glossary that is used by multiple documents including the Virtual Device Driver Reference for OS/2, MMPM/2 Device Driver Reference, Display Device Driver Reference for OS/2, Virtual Device Driver Reference for OS/2, Printer Device Driver Reference for OS/2, Storage Device Driver Reference, GRADD Reference Glossary, Input Output Device Driver Reference and others.

Glossary

This glossary contains terms and definitions that are, for the most part, used for OS/2 products. This is not a complete dictionary of computer terms.

Introduction

This glossary defines many of the terms used in this book. It includes terms and definitions from the IBM Dictionary of Computing, as well as terms specific to the Presentation Manager, but it is not a complete glossary for OS/2.

Other primary sources for these definitions are:

The American National Standard Dictionary for Information Systems, ANSI X3 .172-1990, copyrighted 1990 by the American National Standards Institute, 11 West 42nd Street, New York, New York 10036. These definitions are identified by the symbol (A) after the definition.
The Information Technology Vocabulary, developed by Subcommittee 1, Joint Technical Committee 1, of the International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC JTC1/SC1). Definitions of published parts of this vocabulary are identified by the symbol (I) after the definition; definitions taken from draft international standards, committee drafts, and working papers being developed by ISO/IEC JTC1/SC1 are identified by the symbol (T) after the definition, indicating that final agreement has not yet been reached among the participating National Bodies of SC1.

Glossary

A

B

C

D

DASD - Direct-access storage device.

data bus - A bus used to communicate data internally and externally to and from a processing unit, storage, and peripheral devices. (A) See bus.

data structure - The syntactic structure of symbolic expressions and their storage allocation characteristics. (T)

DBCS Double-byte character set.

DC Device context.

DDB Device-dependent bit map.

deinstantiation - See instantiation.

DevHlp Device helper.

device context (DC) - A logical description of a data destination such as memory, metafile, display, printer, or plotter. See also direct device context, information device context, memory device context, metafile device context, and screen device context.

device driver A file that contains the code needed to attach and use a device such as a display, printer, or plotter.
device driver initialization (init) time See initialization (init) time, device driver.

device driver profile A file with a "DDP" extension, containing a script that is interpreted by the OS/2 DDINSTAL utility. Among other things, it defines which files to copy from installation diskettes to target directories and specifies how the CONFIG.SYS file will be updated.

device helper (DevHlp) (1) A kernel service (memory, hardware interrupt, software interrupt, queuing, semaphore, and so forth) provided to physical device drivers. (2) A callable C-language or assembler-language routine that provides an operating system service for an OS/2 device driver.

device object A device that provides a means of communication between a computer and the outside world. A printer is an example of a device object.

device table A data structure containing a summary of the adapters an adapter device driver supports and a list of the I/O devices attached to each adapter. This data structure is built by the adapter device driver in response to an IOCC_CONFIGURATION IOCM_GET_DEVICE_TABLE request.

direct access storage device (DASD) A device in which access time is effectively independent of the location of the data.

direct memory access (DMA) (1) A technique for moving data directly between main storage and peripheral equipment without requiring processing of the data by the processing unit. (2) The transfer of data between memory and input/output units without processor intervention.

display frame (1) In computer graphics, an area in storage in which a display image can be recorded. (2) In computer micrographics, an area on a microform in which a display image can be recorded.

dispatch table (1) A block of memory, allocated by the graphics engine, for the containment of entry points for use by a display driver. (2) An array of pointers to function-handling routines.

dithering A technique for interleaving dark and light pels so that the resulting image looks smoothly shaded from a distance.

DLL See dynamic link library (DLL)

DMA' Direct memory access.

double-byte character set (DBCS)' A set of characters in which each character is represented by two bytes. Languages such as Japanese, Chinese, and Korean, which contain more characters than can be represented by 256 code points, require double-byte character sets. Because each character requires 2 bytes, the typing, display, and printing of DBCS characters requires hardware and programs that support DBCS. Contrast with single-byte character set.

driver (1) A program (and possibly data files) that contain information needed to run a particular unit, such as a plotter, printer, port, or mouse. See also device driver and printer driver. (2) A system or device that enables a functional unit to operate.

dynamic link library (DLL) A file containing executable code and data bound to a program at load time or run time, rather than during linking. The code and data in a dynamic link library can be shared by several applications simultaneously.

E

F

G

H

handle - (1) An identifier that represents an object, such as a device or a window, to the Presentation Interface. (2) In the Advanced DOS and OS/2 operating systems, a binary value created by the system that identifies a drive, directory, and file so that the file can be found and opened.

handshaking - A method by which two pieces of hardware, such as a personal computer and a plotter, can communicate. Depending upon the devices communicating, handshaking occurs either as a hardware function or through software, such as a device driver.

hard error - An error condition on a network that requires that the network be reconfigured or that the source of the error be removed before the network can resume reliable operation.

hardware palette - The array of RGBs that the physical device is displaying .

heap - An area of free storage available for dynamic allocation by an application. Its size varies depending on the storage requirements of the application.

hex - See hexadecimal

hexadecimal - Pertaining to a system of numbers to the base 16; hexadecimal digits range from 0 through 9 and A through F, where A represents 10 and F represents 15.

hook - A point in a system-defined function where an application can supply additional code that the system processes as though it were part of the function.

hook chain - A sequence of hook procedures that are "chained" together so that each event is passed in turn to each procedure in the chain.

I

IDC - Inter-device-driver communication.

in-memory buffer - A block of memory in the address space of the host machine, used for data transfer.

init time - See initialization time, device driver.

initialization time, device driver - After the OS/2 loads a device driver, it sends it an OS/2 request packet to initialize. During this initialization, certain DevHlp functions are not permitted. Also called init time.

Input/Output Control (IOCtl) - A system service that provides a way for an application to send device-specific control commands to a device driver.

Input/Output Privilege Level (IOPL) - Allows part of a Ring 3 application or device driver to execute at Ring 0.

input router - OS/2 internal process that removes messages from the system queue.

inter-device-driver communication (IDC) - A mechanism that enables a physical device driver to communicate with another physical device driver.

interprocess communication - In the OS/2 operating system, the exchange of information between processes or threads through semaphores, queues, and shared memory.

interrupt - An instruction that directs the microprocessor to suspend what it is doing and run a specified routine. When the routine is complete, the microprocessor resumes its original work. See also routine.

interrupt request (IR) - Broadly, an "interrupt request level", referring to pending or in-service interrupt requests, or to a specific level (for example, IR 4).

interrupt request flag - A bit in the 8259 PIC controller that indicates an interrupt is pending on particular level. The VPIC also maintains a virtual interrupt request flag for each interrupt level for each DOS session.

interrupt service flag - A bit in the 8259 PIC controller that indicates an interrupt request is being serviced. It is cleared when the PIC is sent EOI . The VPIC maintains a virtual interrupt service flag indicating that a simulated interrupt is in-progress in a DOS session.

interrupt time - When a device driver is run because of an interrupt rather than because of an application request. OS/2 device drivers receive interrupts either from the hardware they manage or from the system real- time clock.

During interrupt time, certain DevHlp functions are not permitted. Also, addresses received directly from OS/2 applications might not be valid unless they are converted system addresses.

IOCtl - Input/Output Control.

IOPL - Input/Output Privilege Level.

IORB - Input/Output Request Block.

Input/Output Request Block (IORB) - A data structure defined by this specification that is passed as a parameter on all calls to an adapter device driver. It contains a fixed section, followed by a command-dependent section.

IORBH - Input/Output Request Block Header

IRET - Interrupt return.

IRQ - Interrupt Request.

J

journal

K

L

M

N

P

physical address - A 32-bit byte address giving the actual address in physical storage for a data item.

physical device driver (PDD) - A system interface that handles hardware interrupts and supports a set of input and output functions.

pipe - See named pipe, unnamed pipe.

picture element (pel, pixel) - (1) In computer graphics, the smallest element of a display surface that can be independently assigned color and intensity. (T) . (2) The area of the finest detail that can be reproduced effectively on the recording medium. (3) An element of a raster pattern about which a toned area on a photoconductor can appear.

PIO - Programmed I/O.

pixel - Picture element.

polyfillet - A curve based on a sequence of lines. The curve is tangential to the end points of the first and last lines, and tangential also to the midpoints of all other lines.

polyline - In computer graphics, a sequence of adjoining lines.

pop - To remove an item from the top of a pushdown list. Contrast with push .

prefetch - To locate and load a quantity of data in anticipation of a request.

presence-check function - A Ring 3 (non-privileged) .EXE program that determines whether a given hardware interface is present on a workstation.

PRESENCECHECK - A keyword, interpreted by the DDINSTAL utility, to determine whether to process the device driver profile file, based on the return code from PRESENCECHECK.

printer driver - A file that describes the physical characteristics of a printer, plotter, or other peripheral device, and is used to convert graphics and text into device-specific data at the time of printing or plotting.

Print Manager - In the Presentation Manager, the part of the spooler that manages the spooling process. It also allows the user to view print queues and to manipulate print jobs.

privilege level - A method of protection that allows only certain program instructions to be used by certain programs.

program group - Several programs that can be acted upon as a single entity.

protect mode - A method of program operation that limits or prevents access to certain instructions or areas of storage. Contrast with real mode.

push - To add an item to the top of a pushdown list. Contrast with pop.

Q

queued device context

R

read-only memory basic input/output system (ROM-BIOS) - Microcode in read- only memory that controls basic input/output operations such as interactions with cassettes, diskette drives, hard disk drives, and the keyboard. See also BIOS, NetBIOS.

Note: ROM BIOS allows the user to write programs and add or remove devices without concern for characteristics such as device addresses.

real mode - In the OS/2 operating system, a method of program operation that does not limit or prevent access to any instructions or areas of storage. The operating system loads the entire program into storage and gives the program access to all system resources.

reentrant - The attribute of a program or routine that allows the same copy of the program or routine to be used concurrently by two or more tasks.

removable-media indicator - A flag (bit) indicating that a device permits media removal.

resource - The means of providing extra information used in the definition of a window. A resource can contain definitions of fonts, templates, accelerators and mnemonics; the definitions are held in a resource file.

resurrection - The Presentation Manager event that occurs when switched back from a full-screen DOS or WIN-OS/2 session.

RETF - Return far.

reverse video - A form of highlighting a character, field, or cursor by reversing the color of the character, field, or cursor with its background; for example, changing a red character on a black background to a black character on a red background.

ROM BIOS - Read-Only Memory Basic Input/Output System.

ROP - Raster operation.

RTC - Real-Time Clock.

S

T

U

unnamed pipe

V

W

window coordinates

@@ Line 67: / Line 67: @@
 * [[character mode]]
 * [[clipping]]
-* [[clip limits]] The area of the paper that can be reached by a printer or plotter.
+* [[clip limits]]
-* [[clipping path]] A clipping boundary in world-coordinate space.
+* [[clipping path]]
-* [[code page]] An assignment of graphic characters and control function meanings to all code points; for example, assignment of characters and meanings to 256 code points for an 8-bit code, assignment of characters and meanings to 128 code points for a 7-bit code.
+* [[code page]]
-* [[code point]] A 1-byte code representing one of 256 potential characters.
+* [[code point]]
-* [[code segment]] An executable section of programming code within a load module.
+* [[code segment]]
-* [[color conversion]] Changing one color format to another. Required, for example, when the source color format is different from the destination color format. When going from the monochrome color format to the color format, 1 (one) bits are converted to the image foreground color, and 0 ( zero) bits are converted to the image background color.
+* [[color conversion]]
+* [[color dithering]]
-When going from color to monochrome, all pels that match the passed background color are converted to the image background color of the destination.
+* [[command code]]
+* [[command data block]]
-All other pels are converted to the image foreground color of the destination. The color conversion takes place prior to any mix mode.
+* [[command descriptor block (CDB)]]
-* [[color dithering]] See dithering.
+* [[command modifier]]
-* [[command code]] In this specification, refers to a group of related commands that an adapter device driver can receive.
+* [[compatibility kernel]]
+* [[CON]]
-All command codes have a prefix of &quot;IOCC_&quot;. For example, common I/O requests (such as Read, Write, etc.) are grouped under the command code IOCC_EXECUTE_IO.
+* [[conditional compilation]]
+* [[context hook]]
-* [[command data block]] A data structure defined by the Small Computer System Interface standard to send commands to devices that conform to SCSI standards.
+* [[control program]]
+* [[controller sector buffer]]
-* [[command descriptor block (CDB)]] The structure used to communicate commands from a source to a destination.
-* [[command modifier]] In this specification, a specific operation that an adapter device driver is to perform.
-All command modifiers have a prefix of &quot;IOCM_&quot;. For example, an adapter device driver might receive an IOCC_EXECUTE_IO command with a command modifier of IOCM_READ.
-* [[compatibility kernel]] The portion of the OS/2 kernel that exists to support DOS INT 20, 21, 25, 26, and 27 functions. It acts as an interface to common kernel functionality such as the file system.
-* [[CON]] Character-device name reserved for the console keyboard and screen.
-* [[conditional compilation]]'Processing by the preprocessor of certain specified code in the file, depending on the evaluation of a specified condition.
-* [[context hook]] Similar to a "force flag" in earlier versions of OS/2. These are events, signaled by a virtual device driver, that are processed at task time. Forcing an IRET, and simulating an NMI, can fall into this category.
-* [[control program]] A computer program designed to schedule and to supervise the execution of programs of a computer system.
-* [[controller sector buffer]] One or more buffers, managed by a hardware adapter, to improve I/O transfer rates by helping to match a device and software timing requirements.
 ===D===