Operating System Concepts 10th Edition: Computer System Structure

Computer Storage

• The smallest unit of storage in a computer is a bit.
• A byte is composed of 8 bits.
• A word in computer storage is a group of bytes that can be accessed and processed as a single unit.

Data Measurement

• A kilobyte (KB) is equal to 1,024 bytes.
• Networking measurements are typically given in bits per second (bps).
• A gigabyte (GB) is equal to 1,073,741,824 bytes.

Operating System

• The main function of an operating system is to manage computer hardware resources and provide common services to computer programs.
• A computer system can be divided into hardware and software components.
• The operating system plays a crucial role in managing shared computers like mainframes.

Mobile Devices

• Mobile devices like smartphones and tablets are characterized by their portability, touchscreens, and wireless connectivity.

Operating System Components

• The kernel is the core part of an operating system that manages hardware resources and provides services to applications.
• Interrupt-driven I/O cycle: the CPU executes a program, and when I/O is needed, the CPU sends a request to the I/O device, which then generates an interrupt to the CPU when the I/O operation is complete.

I/O Handling Methods

• Two methods for handling I/O: programmed I/O and interrupt-driven I/O.

Storage Devices

• The basic unit of computer storage is a bit.
• Hard Disk Drives (HDD) consist of a magnetic disk, read/write head, and motor.
• Non-volatile memory (NVM) devices have an advantage over hard disks in terms of faster access time and lower power consumption.

Cache Memory

• Caching: temporarily storing frequently accessed data in a faster memory location to reduce access time.

Input/Output Operations

• Direct Memory Access (DMA) allows high-speed I/O devices to access memory directly, reducing CPU involvement.
• A bootstrap program loads the operating system into memory during the boot process.

CPU and I/O Utilization

• Multiprogramming: running multiple programs concurrently to efficiently utilize CPU and I/O devices.
• Multitasking (timesharing): rapidly switching between multiple programs to create the illusion of simultaneous execution.

Virtual Memory

• Virtual memory provides a mechanism for using secondary storage to supplement main memory, enabling a system to run larger programs than physical memory can hold.

Operating System Modes

• Dual-mode operation: an operating system can run in either user mode or kernel mode.

Device Management

• A device driver manages I/O operations between the operating system and hardware devices.

Process Execution

• Swapping: temporarily transferring a process from main memory to secondary storage to free up memory space, enabling efficient execution of multiple processes in a memory-constrained system.

Interrupt Handling

• A hardware interrupt is triggered by an I/O device completing an operation.

Computer Architecture

• The Von Neumann architecture is a design model for modern computers, featuring a central processing unit, memory, and input/output devices.

Memory Layout

• In a multiprogrammed system, the memory layout differs from a single program system in that multiple programs coexist in memory, requiring memory management and protection mechanisms.