Types of Interrupts:

1. Hardware vs Software Interrupt:

   • Hardware Interrupt: Generated externally by hardware devices (e.g., I/O device, timer) signalling CPU via INTR/NMI pins. Asynchronous to program.
   • Software Interrupt: Generated internally by executing INT n instruction. Synchronous, used for system calls and exception handling.

2. Maskable vs Non-Maskable Interrupt:

   • Maskable (INTR): Can be enabled/disabled by Interrupt Flag (IF). CPU can ignore if IF=0. Used for normal peripherals.
   • Non-Maskable (NMI): Cannot be disabled, always serviced (IF has no effect). For critical events like power failure, memory parity error.

3. Vectored vs Non-Vectored Interrupt:

   • Vectored: Interrupting device supplies vector address (branch address) directly. No polling needed. e.g., Intel RST, TRAP.
   • Non-Vectored: Vector address not supplied; CPU must poll/interrogate devices or jump to fixed address to identify source and then branch.