Software Interrupts in Assembly Language | INT Instruction & IVT Explained

In this BSCS Zoom Class lecture, we dive into the mechanics of Software Interrupts in Computer Organization and Assembly Language (COAL). We break down exactly how the processor pauses its current execution to handle system calls and OS-level events. What You Will Learn in This Lecture: What is a Software Interrupt? The fundamental role of the INT instruction. Interrupt Vector Table (IVT): How the CPU locates the correct service routine using an interrupt vector. Interrupt Service Routine (ISR): How the hardware switches context to execute the handler code. The Stack Mechanics: What happens to EFLAGS, CS, and EIP when an interrupt is triggered. The IRET Instruction: How the processor returns smoothly to the main program. This comprehensive guide simplifies low-level hardware communication, making it highly accessible for computer science students and system programmers alike. Timestamps: 0:00 - Introduction to Interrupts (Hardware vs. Software) 03:15 - The INT Instruction Mechanics 06:40 - Exploring the Interrupt Vector Table (IVT) 11:20 - Inside the Interrupt Service Routine (ISR) 16:50 - Stack Changes During an Interrupt 22:10 - Summary & Student Q&A