Computer System Operation in Operating system || Computer System Organization || Operating System

Summary

This video introduces the concept of computer system organization, focusing on the components like CPUs, device driver files, and memory. It explains how data transfer occurs between the CPU, disk controllers, USB controllers, and graphics adapters through a common bus system. The role of interrupts is detailed, with CPU transferring data between memory and local buffers. The video also covers the bootstrap loader and its function in loading the operating system kernel into main memory. Additionally, the handling of interrupts by the CPU is explained through a diagram showcasing the interaction between the CPU and I/O devices.

Takeaways

• 😀 Modern computer systems contain one or more CPUs, device driver files, and a memory connected through a common bus system.
• 😀 Device controllers such as disk controllers, USB controllers, and graphics adapters manage input/output tasks and interact with the CPU via a bus system.
• 😀 Disk controllers and other device controllers have local buffers to store data temporarily before transferring it to/from the main memory.
• 😀 CPU and device controllers work concurrently, meaning the CPU can continue processing while device controllers perform their tasks.
• 😀 The CPU can transfer data from a local buffer to the main memory when it receives an interrupt signal from a device controller.
• 😀 Interrupt signals are generated by device controllers (like the disk or USB controller) when they have data to send to the CPU.
• 😀 The bootstrap loader program, stored in ROM, is executed when the computer is powered on and loads the operating system kernel into the main memory.
• 😀 The kernel contains essential operating system tasks, including initializing driver files for devices such as the keyboard, mouse, and monitor.
• 😀 When an interrupt signal is received by the CPU, it temporarily stops executing the current program and shifts control to the Interrupt Service Routine (ISR).
• 😀 After executing the ISR, the CPU returns to the original program execution from the point it was interrupted, ensuring smooth program continuation.
• 😀 The diagram provided illustrates the two-stage process of CPU operation: executing user programs and processing interrupts (ISR) triggered by IO devices.

Q & A

What are the three topics discussed in the video about computer system organization?

The three topics discussed in the video are: computer system operation, storage structure, and I/O structure. The video focuses on the first topic, computer system operation.

What is the role of device driver files in a modern computer system?

Device driver files in a modern computer system allow communication between the CPU and various hardware components, such as disk controllers, USB controllers, and graphics adapters. They act as intermediaries to enable hardware to interact with the operating system.

How does a CPU interact with the disk in a modern computer system?

A CPU does not interact directly with the disk. Instead, it communicates with the disk controller through a shared bus. The disk controller manages the disk and transfers data between the local buffer and the disk, with the CPU facilitating data transfer to and from memory.

What happens when the disk controller has data to send to the CPU?

When the disk controller has data to send, it triggers an interrupt signal to the CPU. The CPU then halts its current task, stores the address of the next instruction, and switches to handle the interrupt, transferring data from the disk's local buffer to the main memory.

What is a bootstrap loader and where is it stored?

A bootstrap loader is a program that is executed when a computer is powered on. It loads the operating system kernel into the main memory. The bootstrap loader is stored in ROM (Read-Only Memory) to ensure it is not lost when the computer is powered off.

Why is the bootstrap loader stored in ROM and not RAM?

The bootstrap loader is stored in ROM because ROM is non-volatile, meaning its contents are not erased when the power is turned off. In contrast, RAM is volatile, and any data stored in it would be lost when the computer is powered down.

What is the role of the interrupt service routine (ISR)?

The interrupt service routine (ISR) is a program executed by the CPU to handle an interrupt. It manages tasks such as transferring data between memory and device buffers, allowing the CPU to return to its original task after completing the interrupt-related work.

How does the CPU manage instructions during an interrupt?

When an interrupt occurs, the CPU stops executing the current instruction and stores the address of the next instruction in the program counter. It then shifts control to the ISR, handles the interrupt, and returns to the original program once the ISR is complete.

What is the significance of local buffers in device controllers like the disk and USB controllers?

Local buffers in device controllers temporarily store data being transferred between devices and memory. These buffers allow the devices to work independently of the CPU, enabling efficient data transfer without interrupting the CPU's current tasks.

How are interrupts handled in a modern computer system?

In a modern computer system, when a device (such as a disk or USB controller) has data ready, it sends an interrupt signal to the CPU. The CPU stops its current execution, handles the interrupt by executing the ISR, and then resumes its previous tasks after the interrupt is processed.