Software Routines - IO Organization - Computer Organization and Architecture

TL;DR

This content explains how software routines, specifically interrupt service routines, are executed when an interrupt is triggered in a CPU.

Transcript

hello everyone in this session let us understand about software routines are the interrupt service routines which are going to get executed when an interrupt is triggered let us say a keyboard interrupt the cpu when the keyboard interrupt the cpu cpu should be able to execute the keyboard's interrupt service routine every device that is connected t... Read More

Key Insights

• 🐕‍🦺 Interrupt service routines are necessary for handling interrupts from different IO devices connected to a CPU.
• 🐕‍🦺 Each device has its own service routine stored in the main memory.
• 😒 The CPU uses pointers to determine which service routine to execute.
• 🐕‍🦺 Interrupts cause the CPU to suspend its current program execution and jump to the corresponding service routine.
• 🐕‍🦺 The program counter value of the current program is saved before executing the service routine.
• 🐕‍🦺 Once the service routine is executed, the device is considered completely serviced.
• 🐕‍🦺 Interrupt service routines are crucial for multitasking and ensuring smooth operation of IO devices.

Questions & Answers

Q: What are interrupt service routines?

Interrupt service routines (ISRs) are software routines that are executed by a CPU when a device interrupts its current program execution.

Q: How are interrupt service routines stored in the main memory?

Each IO device has its own portion of the main memory reserved for its service routine, with pointers indicating the start and end addresses of the routine.

Q: How does the CPU know which service routine to execute?

The CPU examines special bits associated with each interrupt and jumps to the appropriate service routine based on the value of these bits.

Q: What happens to the program being executed when an interrupt occurs?

The CPU saves the address of the next instruction to be executed in a specific location in the main memory or in the system stack before jumping to the interrupt service routine.

Summary & Key Takeaways

• Interrupt service routines are executed when a device interrupts the CPU, and each IO device has its own service routine loaded in the main memory.

• Service routines for different devices are stored in separate portions of the main memory.

• When a device interrupts the CPU, the CPU jumps to the corresponding service routine and executes the instructions within that range.