Interrupts: Difference between revisions

An interrupt is a message from a device, such as the keyboard, to the CPU, telling it to immediately stop whatever it is currently doing and do something else. For example, the keyboard controller sends an interrupt when a key is pressed. To know what to do when a specific interrupt arise, the CPU has a table called the '''[[IDT]]''' which is setup by the OS, and stored in memory. There are 256 interrupts, numbered from 0 to 255, but only 16 are used by devices. These are called '''IRQs''' (Interrupt ReQuest) or hardware interrupts. The 16 IRQs are numbered from 0 to 15. Applications can call interrupts with the INT instruction, such as: