P picture

P picture

Predictive-coded picture. A picture type that uses the closest past I or P picture (forward prediction) as the reference for motion-compensated prediction.

preimaging

The process of building a movie frame in a memory buffer before it is displayed.

PRI

See ISDN Primary Rate Interface.

primary display

Also referred to as primary monitor and primary display device. The primary display in a multiple monitor system is the one that contains the origin (0,0). Other than this, the primary display in Windows 2000 and later can be any display.

primary monitor

See primary display.

print monitor

A user-mode DLL responsible for directing a print data stream from the print spooler to an appropriate port driver.

For more information see the topic, Writing a Print Monitor.

print processor

A user-mode DLL responsible for converting a print job's spooled data into a format that can be sent to a print monitor.

For more information see the topic, Writing a Print Processor.

Printer Control Language (PCL)

A page description language developed by Hewlett Packard (HP) and used by many HP laser and inkjet printers.

Printer Font Metrics (PFM)

Files that describe fonts for a printer.

printer job language (PJL)

A language that implements communication between a bidirectional printer device and a computer. PJL was defined and implemented by Hewlett-Packard.

printer-sticky

A printer property page setting that applies to a single printer. For example, the amount of memory installed on a particular printer is a printer-sticky setting.

Contrast with document-sticky.

priority

An attribute of a thread that determines when and how often the thread is scheduled to run. For a running thread, its priority falls into either of two classes, each class having sixteen levels:

Variable priority class has values in the range 0 to 15. This class is used by most threads.

Threads with variable priority are always preemptible; that is, they are scheduled to run round-robin with other threads at the same level. In general, the kernel manages a variable-priority thread as follows: when the thread is interactive with a user, its priority is high (given a boost); otherwise, its priority decays by one level per quantum that the thread runs until it reaches its original programmer-defined base priority level.

Real-time priority class has values in the range 16 to 31. This class is used by time-critical threads, making such a thread preemptible only by a thread with higher priority.

Note that any thread, whatever its priority attribute, is always preemptible by a software or hardware interrupt.

priority boosts

A set of system-defined constant values, supplied when drivers complete an IRP. For example, when drivers for interactive devices call IoCompleteRequest, they usually specify a device-type-specific priority boost value. The boost is added to the priority of the user-mode thread that originally requested the I/O operation to compensate for that thread's wait on the I/O.

probe

To check that a memory address range is in user-mode address space, and that the range can be read or written in the current process context. See ProbeForRead and ProbeForWrite.

process object

A kernel-defined control object type, representing the virtual address space and control information necessary for the execution of a set of thread objects. A user-mode process object defines the base priority, default affinity, and directory table base value for its threads and for any child processes it creates. Every user-visible process object is implemented through the use of an embedded kernel-mode process object.

A kernel-mode-only process object must be initialized before any thread objects that belong to the process.

property

An aspect of the device or stream that can be set or retrieved, such as volume level.

property set

A uniquely identified set that represents types of related information.

property set

A technique defined to set and get properties on a driver. Each property set has a unique identifier, which represents types of related information and is used to access the property set.

property sets (WDM Streaming property sets)

WDM Streaming-defined mechanism to set and get properties on a driver.

protected subsystem

A server that appears to perform operating system functions for its native applications and subsystem-specific drivers by calling system services. A protected subsystem runs in user mode and its interface to end users emulates another operating system, such as Windows or POSIX, on top of the NT kernel.

See also integral subsystem.

Pscript

Abbreviation for the Microsoft Postscript Printer Driver.

PSTN

See Public Switched Telephone Network.

PTE

Page table entry. The Memory Manager uses a PTE to represent the state of a virtual page.

Public Switched Telephone Network (PSTN)

The public telephone network provided by local and long-distance telecommunications carriers. This network includes both a digital backbone and the analog wiring still used in many residences. The term Plain Old Telephone Service (POTS) is often used to refer to PSTN, but this term should be distinguished from PSTN since it is limited to the analog portion of the PSTN.

pulse

To set an event to the Signaled state, satisfy as many waiters on the event as possible, and to reset the event to the Not-Signaled state.

Px64

A draft standard for motion video compression in videophone and teleconferencing applications, designed for 64-Kbps transmission channels. Also called CCITT Recommendation H.261.