1.4 Operating-System Operations

Question 1

An operating system provides the environment within which programs are _______.

Answer 1

executed

Question 2

The initial program that a computer runs when powered up or rebooted is called the _______.

Answer 2

bootstrap program

Question 3

The bootstrap program is typically stored in _______.

Answer 3

firmware

Question 4

The bootstrap program initializes all aspects of the system, including _______.

Answer 4

CPU registers, device controllers, memory contents

Question 5

The bootstrap program must locate the _______ and load it into memory.

Answer 5

operating-system kernel

Question 6

Once the kernel is loaded and executing, it starts providing _______ to the system and its users.

Answer 6

services

Question 7

System programs loaded into memory at boot time become _______.

Answer 7

system daemons

Question 8

On Linux, the first system program that starts many other daemons is _______.

Answer 8

systemd

Question 9

If there are no processes to execute, an operating system will sit quietly, waiting for something to _______.

Answer 9

happen

Question 10

Events are almost always signaled by the occurrence of an _______.

Answer 10

interrupt

Question 11

A trap (or an exception) is a software-generated interrupt caused by an error or a specific request from a user program that an operating-system service be performed by executing a _______.

Answer 11

system call

Question 12

An example of an error that can cause a trap is _______.

Answer 12

division by zero

Question 13

Another example of an error that can cause a trap is _______.

Answer 13

invalid memory access

Question 14

One of the most important aspects of operating systems is the ability to run multiple programs, as a single program cannot, in general, keep either the CPU or the I/O devices busy at all times. This is known as _______.

Answer 14

multiprogramming

Question 15

In a multiprogrammed system, a program in execution is termed a _______.

Answer 15

process

Question 16

The operating system keeps several processes in _______ simultaneously.

Answer 16

memory

Question 17

When a process needs to wait for some task, such as an I/O operation, the CPU would switch to _______ in a multiprogrammed system.

Answer 17

another process

Question 18

In a non-multiprogrammed system, the CPU would sit _______.

Answer 18

idle

Question 19

Multitasking is a logical extension of _______.

Answer 19

multiprogramming

Question 20

In multitasking systems, the CPU executes multiple processes by _______ among them.

Answer 20

switching

Question 21

When a process executes, it typically executes for only a _______ time before it either finishes or needs to perform I/O.

Answer 21

short

Question 22

Interactive I/O may take a long time to complete, often bounded by the user’s _______ speed.

Answer 22

typing

Question 23

Having several processes in memory at the same time requires some form of _______ management.

Answer 23

memory

Question 24

Making the decision of which process will run next is known as _______ scheduling.

Answer 24

CPU

Question 25

A common method for ensuring reasonable response time in a multitasking system is _______ memory.

Answer 25

virtual

Question 26

The main advantage of virtual memory is that it enables users to run programs that are larger than actual _______ memory.

Answer 26

physical

Question 27

Multiprogramming and multitasking systems must also provide a _______ system.

Answer 27

file

Question 28

To ensure orderly execution, the system must also provide mechanisms for process _______ and communication.

Answer 28

synchronization

Question 29

The system may ensure that processes do not get stuck in a _______.

Answer 29

deadlock

Question 30

A properly designed operating system must ensure that an incorrect (or malicious) program cannot cause other programs or the operating system itself to execute incorrectly. True or False?

Answer 30

True

Question 31

What are the two separate modes of operation in an operating system?

Answer 31

User mode and kernel mode

Question 32

The bit that indicates the current mode of operation in a computer system is called the _______.

Answer 32

mode bit

Question 33

In kernel mode, the mode bit is set to _______.

Answer 33

0

Question 34

In user mode, the mode bit is set to _______.

Answer 34

1

Question 35

When a user application requests a service from the operating system, the system must transition from _______ to _______ mode.

Answer 35

user mode to kernel mode

Question 36

The dual mode of operation provides protection for the operating system from _______ users.

Answer 36

errant

Question 37

Privileged instructions can only be executed in _______ mode.

Answer 37

kernel

Question 38

An attempt to execute a privileged instruction in user mode is treated as _______.

Answer 38

illegal

Question 39

Examples of privileged instructions include _______.

Answer 39

* I/O control * Timer management * Interrupt management

Question 40

Intel processors have _______ separate protection rings.

Answer 40

four

Question 41

In Intel processors, ring 0 is _______ mode.

Answer 41

kernel

Question 42

ARMv8 systems have _______ modes.

Answer 42

seven

Question 43

The virtual machine manager (VMM) has more privileges than user processes but fewer than the _______.

Answer 43

kernel

Question 44

The life cycle of instruction execution in a computer system starts with control residing in the _______.

Answer 44

operating system

Question 45

System calls provide the means for a user program to ask the operating system to perform tasks reserved for the operating system on the user program’s behalf. True or False?

Answer 45

True

Question 46

A system call is usually invoked in the form of a _______ to a specific location in the interrupt vector.

Answer 46

trap

Question 47

When a system call is executed, it is typically treated by the hardware as a _______ interrupt.

Answer 47

software

Question 48

The kernel examines the interrupting instruction to determine what _______ has occurred.

Answer 48

system call

Question 49

If a user program fails by executing an illegal instruction, the hardware traps to the _______.

Answer 49

operating system

Question 50

When a program error occurs, the operating system must terminate the program _______.

Answer 50

abnormally

Question 51

An appropriate error message is given, and the memory of the program may be _______.

Answer 51

dumped

Question 52

We must ensure that the operating system maintains control over the ___

Answer 52

CPU

Question 53

We cannot allow a user program to get stuck in an infinite loop or to fail to call ___ and never return control to the operating system.

Answer 53

system services

Question 54

To accomplish the goal of maintaining control, we can use a ___.

Answer 54

timer

Question 55

A timer can be set to interrupt the computer after a specified ___.

Answer 55

period

Question 56

The period of a timer may be fixed (for example, 1/60 second) or ___.

Answer 56

variable

Question 57

A variable timer is generally implemented by a fixed-rate clock and a ___.

Answer 57

counter

Question 58

The operating system sets the ___.

Answer 58

counter

Question 59

Every time the clock ticks, the counter is ___.

Answer 59

decremented

Question 60

When the counter reaches 0, an ___ occurs.

Answer 60

interrupt

Question 61

A 10-bit counter with a 1-millisecond clock allows interrupts at intervals from 1 millisecond to ___ milliseconds.

Answer 61

1,024

Question 62

Before turning over control to the user, the operating system ensures that the timer is set to ___.

Answer 62

interrupt

Question 63

If the timer interrupts, control transfers automatically to the operating system, which may treat the interrupt as a ___ or may give the program more time.

Answer 63

fatal error

Question 64

Instructions that modify the content of the timer are ___.

Answer 64

privileged