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A hardware interrupt is a condition related to the state of the hardware that may be signaled by an external hardware device, e.g., an interrupt request (IRQ) line on a PC, or detected by devices embedded in processor logic (e.g., the CPU timer in IBM System/370), to communicate that the device needs attention from the operating system (OS) [7] or, if there is no OS, from the bare metal ...
Interrupts are signals sent by hardware devices to the CPU alerting it that an event occurred to which it should react. For example, hardware timers send interrupts to the CPU at regular intervals. Most operating systems execute a HLT instruction when there is no immediate work to be done, putting the processor into an idle state .
BIOS interrupt calls perform hardware control or I/O functions requested by a program, return system information to the program, or do both. A key element of the purpose of BIOS calls is abstraction - the BIOS calls perform generally defined functions, and the specific details of how those functions are executed on the particular hardware of the system are encapsulated in the BIOS and hidden ...
A BIOS interrupt handler would then translate the program's request to match the hardware that was actually present. The SMM in the 386SL is a better way to do this. Some 8-bit home computers used the NMI line to permit a "warm start" if the system had locked up.
In a computer, an interrupt request (or IRQ) is a hardware signal sent to the processor that temporarily stops a running program and allows a special program, an interrupt handler, to run instead. Hardware interrupts are used to handle events such as receiving data from a modem or network card , key presses, or mouse movements.
In computer systems programming, an interrupt handler, also known as an interrupt service routine or ISR, is a special block of code associated with a specific interrupt condition. Interrupt handlers are initiated by hardware interrupts, software interrupt instructions, or software exceptions , and are used for implementing device drivers or ...
The IRR specifies which interrupts are pending acknowledgement, and is typically a symbolic register which can not be directly accessed. The ISR register specifies which interrupts have been acknowledged, but are still waiting for an end of interrupt (EOI). The IMR specifies which interrupts are to be ignored and not acknowledged.
The device which originally requested the interrupt therefore does not get its interrupt serviced, so a new interrupt is generated (or is not cleared) and the processor becomes swamped with continuous interrupt signals. Any operating system can live lock under an interrupt storm caused by such a fault.