- 2069 Poush · 2 marks
Hardware vs software interrupts
Short answer
Hardware interrupts come from external devices (e.g., NMI, INTR) and are asynchronous and maskable. Software interrupts are caused by instructions (e.g., INT n) and are synchronous and non-maskable.
Differentiate between hardware and software interrupts.
| Basis | Hardware interrupt | Software interrupt |
|---|---|---|
| Source | External device or signal on an interrupt pin | An instruction in the program |
| Examples | 8085: TRAP, RST 5.5/6.5/7.5, INTR; 8086: NMI, INTR | 8085: RST 0–7; 8086: INT n, INT 3, INTO |
| Timing | Asynchronous: can happen at any time | Synchronous: occurs at a known place in the program |
| Masking | Most can be masked (except TRAP, NMI) | Cannot be masked |
| Acknowledge | Needs INTA' (for INTR) | No acknowledge cycle |
| Use | Servicing I/O devices, emergencies | System calls, debugging, exceptions |
✓ Answer checked by Claude Opus 5.5 (high effort)
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