Hardwareafbrydelser

Hardwareafbrydelser, often referred to as hardware interrupts, are signals generated by hardware devices to notify the CPU of an event that requires immediate attention. These events can range from a user pressing a key on the keyboard, a mouse click, a disk drive completing a read or write operation, to a network card receiving data. When a hardware device generates an interrupt, it temporarily suspends the CPU's current task and directs its attention to handling the interrupt.

The process of handling a hardware interrupt typically involves a sequence of steps. The hardware device asserts an interrupt request (IRQ) line, which is connected to an interrupt controller. The interrupt controller then signals the CPU, indicating that an interrupt has occurred. The CPU, upon receiving the interrupt signal, completes its current instruction and then enters an interrupt service routine (ISR). The ISR is a special piece of software designed to handle the specific interrupt. It identifies the source of the interrupt, performs the necessary actions to service the request, and then returns control to the interrupted program.

Interrupts are crucial for efficient system operation. Without them, the CPU would have to constantly poll hardware devices to check if they require any attention, a process known as polling, which is very inefficient and wastes valuable processing time. Hardware interrupts allow the CPU to perform other tasks while waiting for hardware events, thus improving the overall responsiveness and performance of the computer system. Different hardware devices are assigned different priority levels for interrupts, ensuring that critical events are handled before less important ones.