Chapter 1: Introduction

Question 1

What is an operating system?

Answer 1

A program that manages a computer’s hardware. It also provides a basis for application programs and acts as an intermediary between the computer hardware.

Question 2

Caching

Answer 2

copying information into faster storage system. main memory can be viewed as a last cache for secondary storage.

Question 3

What is dual mode?

Answer 3

operation allows operating system to protect itself and other system components.

Question 4

What is a trap?

Answer 4

generated interrupt caused either by an error or a user request. stops normal execution.

Question 5

What is the kernel?

Answer 5

“The one program running at all times on the computer”

Question 6

Goals of Operating System

Answer 6

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

Question 7

Resource allocator

Answer 7

manages and allocates resources

Question 8

Control program

Answer 8

controls the execution of user programs and operations of I/O devices

Question 9

Process

Answer 9

An executing program

Question 10

Resource

Answer 10

Anything that is needed for a process to run:
Memory
Space on a disk
The CPU

Question 11

Storage systems organized in hierarchy

Answer 11

Speed
Cost
Volatility

Question 12

volatile storage

Answer 12

loses its

contents when the power to the device is removed

Question 13

Solid-state disks

Answer 13

have several variants but in general are faster than

magnetic disks and are nonvolatile

Question 14

What are two tasks that an operating system is responsible for from the perspective of the computer?

Answer 14

Manages resource allocation, execution of program and hardware.

Question 15

From the perspective of the computer, what is the purpose of the operating system?

Answer 15

resource management and controlling programs.

Question 16

What are methods of parameter passing that are used in an invocation of a system call?

Answer 16

table
registers
stack

Question 17

Space-multiplexed

Answer 17

sharing is the division of a resource into two or more distinct units and then the allocation of the individual units to processes.

Question 18

Time-multiplexed

Answer 18

sharing is when one process can use the entire resource for a period of time and then another process uses it at a later time.

Question 19

Timesharing (multitasking)

Answer 19

is logical extension in which CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing
Response time should be < 1 second
Each user has at least one program executing in memory process
If several jobs ready to run at the same time  CPU scheduling
If processes don’t fit in memory, swapping moves them in and out to run
Virtual memory allows execution of processes not completely in memory

Question 20

What are the two types of isolated sharing that is practiced by the operating system when multi-programming is in use? Provide an example of each type.

Answer 20

Time-multiplex: library book

space-multiplex: parking lot

Question 21

What does it mean to say that the operating system is in dual mode and what is the purpose of dual mode?

Answer 21

operation allows operating system to protect itself and other system components. Uses user mode and kernel mode. Also uses interrupts and traps.

Question 22

How does the operating system protect itself from erroneous application program behavior?

Answer 22

Dual mode operation protects it.

Question 23

What is the purpose of a cache? Where is it usually in the memory hierarchy?

Answer 23

copying information into faster storage system; main memory can be viewed as a last cache for secondary storage.
Below registry and above main memory.

Question 24

Main memory

Answer 24

is usually too small to store all needed programs and data permanently. a volatile storage device that loses its contents when power is turned off or otherwise lost.

Question 25

Bootstrap program

Answer 25

is loaded at power-up or reboot
Typically stored in ROM or EEPROM, generally known as firmware
Initializes all aspects of system
Loads operating system kernel and starts execution

Question 26

What is the difference between a program and a process?

Answer 26

A process is the way the program itself is executed.