DDK Glossary - I
From EDM2
(Redirected from Interrupt service flag)
- 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.