Operating System Concepts - Chapter 1: Introduction

Flashcards reviewing fundamental concepts from Chapter 1 of Operating System Concepts, including computer system structures, interrupts, storage hierarchy, dual-mode operation, process management, and computing environments.

What is an operating system?

A program that acts as an intermediary between a user of a computer and the computer hardware.

What are the three main goals of an operating system?

1. Execute user programs and make solving user problems easier. 2. Make the computer system convenient to use. 3. Use the computer hardware in an efficient manner.

What are the four main components of a computer system?

Hardware, operating system, application programs, and users.

What components are shown in this high-level structure of a computer system?

Computer hardware, operating system, system and application programs (such as compiler, assembler, text editor, database system), and users (user 1, user 2, user 3, …, user n).

What is the function of the operating system as a resource allocator?

It manages all system resources and decides between conflicting requests for efficient and fair resource use.

What is the function of the operating system as a control program?

It controls the execution of programs to prevent errors and improper use of the computer.

What is the kernel in an operating system?

The kernel is the one program running at all times on the computer.

What is a bootstrap program and where is it stored?

It is a program loaded at power-up or reboot that initializes all aspects of the system, loads the operating system kernel, and starts execution. It is typically stored in ROM or EPROM as firmware.

How does a device controller inform the CPU that it has finished an operation?

By causing an interrupt.

What is a trap or exception?

A software-generated interrupt caused either by an error or a user request.

What events and process states are illustrated in this interrupt timeline diagram?

The CPU executing a user process, receiving an I/O request, the I/O device transferring data while idle/active, and the CPU handling I/O interrupt processing when the transfer is done.

What is Direct Memory Access (DMA)?

A mechanism used for high-speed I/O devices where the device controller transfers blocks of data directly to main memory without CPU intervention, generating only one interrupt per block.

What is the hierarchy of storage devices shown in this diagram, ordered from top to bottom?

Registers, cache, main memory, solid-state disk, hard disk, optical disk, and magnetic tapes.

What is caching in computer systems?

The process of copying information temporarily from slower storage into a faster storage system (cache) to enable faster access.

What is the key difference between multiprogramming and timesharing (multitasking)?

Multiprogramming organizes jobs so the CPU always has one to execute when waiting for I/O, whereas timesharing switches CPU jobs so frequently (response time < 1 second) that users can interact with each running program.

What memory layout structure is shown in this diagram for a multiprogrammed system?

Main memory divided into space for the operating system starting at address 0, followed by space allocated for multiple user jobs (job 1, job 2, job 3, job 4) up to memory capacity (512M).

What is dual-mode operation and why is it needed?

A hardware feature providing user mode (mode bit = 1) and kernel mode (mode bit = 0) that allows the operating system to protect itself and other system components from unauthorized or erroneous actions.

How does execution transition between user mode and kernel mode as depicted in this diagram?

A user process executes a system call, which traps into kernel mode (mode bit set to 0) to execute the system call, and then returns to user mode (mode bit reset to 1).

How does an operating system use a timer to prevent process CPU hogging?

It sets a counter decremented by the physical clock before scheduling a process; when the counter reaches zero, an interrupt is generated so the OS can regain control or terminate a process that exceeds its allotted time.

What is the difference between a program and a process?

A program is a passive entity (such as code stored on disk), whereas a process is an active entity representing a program in execution.

What process management activities are performed by the operating system?

Creating and deleting user/system processes, suspending and resuming processes, and providing mechanisms for process synchronization, process communication, and deadlock handling.

What path does datum 'A' follow as it migrates through storage levels in this diagram?

It moves from hard disk to main memory, then to cache, and finally into a hardware register.

What is cache coherency in multiprocessor environments?

A hardware requirement ensuring that all CPUs accessing a shared datum in their respective caches receive the most recent value.

What is the difference between protection and security in an operating system?

Protection is any mechanism for controlling access of processes or users to resources defined by the OS, whereas security is the defense of the system against internal and external attacks.

What is the difference between compute-server and file-server systems?

Compute-server systems provide an interface for clients to request services (such as database queries), while file-server systems provide an interface for clients to store and retrieve files.

How does a Peer-to-Peer (P2P) network model function?

Nodes are not distinguished as fixed clients or servers; all nodes are peers that can act as clients, servers, or both by registering or discovering services across the network.

What are the three cloud computing service models discussed in the lecture?

Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS).