- intermediate driver
- An intermediate driver processes I/O requests "between" the highest-level driver (frequently a file system driver) and the lowest-level driver that controls the hardware device for which the request is bound.
See also class driver and layered driver.
Examples of intermediate drivers include the ftdisk driver, which supports fault tolerance, other filter drivers, and many class drivers, particularly those layered over mass-storage device drivers.
- interpolation
- The process of averaging pixel information when scaling an image. When reducing the size of an image, pixels are averaged to create a single new pixel; when an image is scaled up in size, additional pixels are created by averaging pixels of the smaller image.
- interrupt
- An asynchronous hardware signal that is detected by the processor. An interrupt usually indicates that a peripheral device needs service. An interrupt causes the processor to save the current state, to branch to a fixed location, and to resume execution at that location.
See also IDT.
- interrupt dispatch table
- See IDT.
- interrupt object
- A kernel-mode-only, kernel-defined control object type, used to connect a hardware interrupt source (see DIRQL) and an ISR to an IDT entry, or to connect an ISR and an interrupt transfer routine (dependent on the ISR at its IRQL) to a second-level IDT entry.
Each interrupt object:
- Can be associated with a single IDT entry (and, therefore, with a single processor in an SMP machine)
- Is either LevelSensitive or Latched, depending on the platform, I/O bus, or device
- Can be one of several interrupt objects associated with a given IDT entry if and only if every interrupt object for that entry is of a single type (LevelSensitive or Latched)
For a second-level IDT entry, an ISR (such as an ISR for a bus adapter that is associated with a first-level IRQL) routes the interrupt to the device-specific interrupt transfer routine for service, using its entry in the IDT.
When more than one set of interrupt objects is connected to the same first-level IDT entry, the corresponding ISRs are called in the same order in which they were connected.
For more information see the topic, Interrupt Objects and ISRs.
- intra
- The representation of picture content without the use of prediction. Intra pictures do not using any previously-decoded picture as a reference. See also I picture
- invalid page
- A page-sized range of virtual addresses for which a page fault occurs when any address in the range is referenced. For drivers, referencing an invalid page causes a fatal page fault unless the driver is running at an IRQL <= APC_LEVEL when the reference occurs.
- Inverse Discrete Cosine Transform
- See IDCT
- IOCTL
- I/O control code. A system-defined or vendor-defined control code that is used to identify I/O control operations. These control codes are contained in I/O request packets, if the IRP code is IRP_MJ_DEVICE_CONTROL or IRP_MJ_INTERNAL_DEVICE_CONTROL.
For more information, see Using I/O Control Codes.
- IPC
- Interprocess communication. The NT-based system has two defined, message-passing mechanisms for IPC:
LPC, defining the port object type with a server process that supplies system (port) services to local (using the same physical memory on a single system) client processes
RPC, with a system-supplied run-time library that implements such RPC capabilities as binding a client process in one address space with a server process in another address space and sending necessary messages to make a remote procedure call possible
- IRB
- I/O request block. An IRB is a block of data that describes an operation to perform.
- IrDA
- Infrared Data Association.
- IRP code
- Short for "IRP function code". See IRP Major Function Codes.
- IRP sink pin
- Responds to IOCTL_KS_READ_STREAM and IOCTL_KS_WRITE_STREAM requests.
- IRP source pin
- Issues IOCTL_KS_READ_STREAM and IOCTL_KS_WRITE_STREAM requests.
- IRP_MJ_Xxx
- IRP major function code. One of a predefined class of IRPs that a driver can accept.
For more information see the topic, IRP Major Function Codes.
- IRQ
- Interrupt request line. A hardware line over which a peripheral device, bus controller, other processor, or the kernel signals a request for service to the microprocessor.
See interrupt.
- IRQL
- Interrupt request level. The hardware priority level at which a given kernel-mode routine runs, masking off interrupts with an equivalent or lower IRQL on the processor. A routine can be preempted by an interrupt with a higher IRQL.
Running at raised IRQL on a given processor has no effect on the IRQL of any other processor in a symmetric multiprocessor machine.
For more information see the topic, Managing Hardware Priorities.
See also IDT, interrupt object, IRQ, ISR, multiprocessor machine, and priority.
- ISA
- Industry standard architecture. A standard defining the architecture of the PC I/O bus.
Also called AT bus standard.
- ISDN
- See Integrated Services Digital Network.
- ISDN basic rate interface
- ISDN basic rate interface (BRI) consists of one D channel and two B channels. The ISDN D channel is used for signaling. The B channels each provide 64 Kbps of data capacity with a combined capability of 128 Kbps. The second B channel can be configured to support voice or data traffic.
- ISDN primary rate interface
- In the United States, ISDN primary rate interface (PRI) consists of one D channel and 23 B channels. The D channels are used for signaling. The B channels each provide 64 Kbps of data capacity with a combined capability of 1472 Kbps.
- ISDN terminal adapter
- An ISDN terminal adapter is a device that is used as a modem in a Windows ISDN installation.
- ISDN-TA
- See ISDN terminal adapter.
- ISO
- International Standards Organization.
- isochronous transfer
- A transfer type that provides a steady, timing-critical data transmission without regard to guaranteed delivery of data.
- isolation
- The Plug and Play process by which cards on an ISA bus are distinguished from each other after system startup.
- ISR
- Interrupt service routine. A routine whose purpose is to service a device when it generates an interrupt.
For more information see the topic, Interrupt Objects and ISRs.
