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Basic Concepts of Computer System Operations
Jul 22, 2024
Operating System: Basic Concepts of Computer System Operations
Introduction
Review of the last lecture: Introduction to Operating Systems
Today's focus: Basic concepts needed to understand Operating Systems, specifically the structure of the computer system
Importance of understanding computer system structure for grasping how operating systems work
Modern General Purpose Computer System
Consists of one or more CPUs (central processing units)
CPUs: The brain of the computer; responsible for all computations and processing
Common misconceptions about CPU: It's not the entire box, but a small chip on the motherboard
Device controllers connected via a common bus to shared memory
Components and Their Connections
CPU
: Central processing unit
Device Controllers
: Control specific types of devices (e.g., disk controller, USB controller, video adapter)
Common Bus
: Connects the CPU and device controllers
Shared Memory
: Accessed by the CPU and device controllers for executing tasks
Key Points
Device controllers handle the functioning of specific hardware devices
CPU and device controllers can execute tasks concurrently (simultaneously)
Importance of memory controllers to ensure orderly, synchronized access to shared memory
Terms and Concepts
Bootstrap Program
The initial program run when a computer is powered up or rebooted
Stored in ROM (Read Only Memory)
Responsible for loading the OS and starting execution
Loads the OS kernel into the main memory
Interrupt
Triggered by hardware or software, signals the CPU to stop its current task and execute a different task
Interrupts can be hardware-initiated or software-initiated (system call/monitor call for software)
CPU stops current work, executes the interrupt service routine, and then resumes its previous task
System Call (Monitor Call)
A type of interrupt triggered by software
Executed via a special operation called a system call
Response to Interrupts
Step 1
: CPU is interrupted and stops its current task
Step 2
: Transfers execution to the starting address of the interrupt service routine (ISR)
Step 3
: ISR executes
Step 4
: CPU resumes the interrupted task upon completion of the ISR
Summary
Basic introduction to computer system operations
Explanation of the structure and functioning of the computer system components
Discussion on Bootstrap programs, interrupts, and system calls
Next lecture: Storage structures and memory
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