Operating Systems Midterm

Question 1

operating system definition

Answer 1

a program that acts as an intermediary b/w a user of a computer and the computer hardware

Question 2

operating system goals

Answer 2

execute user programs and make solving user problems easier, make the computer system convenient to use, use computer hardware efficiently

Question 3

computer system can be divided into four components

Answer 3

hardware, operating system, application programs, users

Question 4

bootstrap program definition

Answer 4

the first program that a computer will run when you push its power button

Question 5

what does a bootstrap program do

Answer 5

initializes the hardware system, loads the OS kernel, and starts execution

Question 6

where is the bootstrap program located

Answer 6

read-only memory (ROM) or EPROM, aka firmware

Question 7

volatile

Answer 7

loses its contents when power to the device is removed (ex: main memory)

Question 8

nonvolatile

Answer 8

loss of power does not result in loss of content (ex: solid-state disks, magnetic disks, optical disks, magnetic tapes; also flash memory and NVRAM, which is DRAM with battery backup power)

Question 9

software-generated interrupt

Answer 9

code error (exception) or system call (trap)

Question 10

hardware-generated interrupt

Answer 10

keyboard, insert ethernet cord

Question 11

cache

Answer 11

a temporary storage system for easy/faster access to recently used information

Question 12

when new information is needed but not in the cache, what will happen?

Answer 12

it will be loaded into the cache

Question 13

two design issues for cache

Answer 13

size and management/replacement

Question 14

if the cache size is too big

Answer 14

too expensive

Question 15

if the cache size is too small

Answer 15

slows down performance

Question 16

cache management/replacement refers to

Answer 16

figuring out when to remove or replace data in the cache

Question 17

cache coherency

Answer 17

in multi-processor systems, multiple CPUs, each with own cache; copies of same data on different caches should be kept updated

Question 18

asymmetric architecture

Answer 18

one CPU/machine standby (as a master) to monitor/control others (as slaves)

Question 19

symmetric architecture

Answer 19

monitor each other (in cluster), equal role to run tasks, tasks may be divided evenly among CPUs/computers

Question 20

how does the OS protect itself from other system components?

Answer 20

dual mode and timer

Question 21

dual mode

Answer 21

refers to kernel mode and user mode: trap in user mode, then switch to kernel mode to the OS so that the OS can check about the privileged instruction to see if it should be executed or not, return from trap generated interrupt and go back to user mode

Question 22

timer

Answer 22

set the timer to interrupt periodically so OS can check if a program uses too much CP time (e.g., infinite loop) – terminate if so, otherwise return CPU control back to the program

Question 23

what is the unit of work in a system?

Answer 23

a process

Question 24

difference between a program and a process

Answer 24

process: an initiated program; a program loaded into main memory and in execution
a program is passive while a process is active

Question 25

to execute a program, what must happen?

Answer 25

its instructions and data must be in main memory

Question 26

cloud computing

Answer 26

delivers computing, storage, and applications as services across a network

Question 27

CLI stands for ? and allows ?

Answer 27

command-line interface; it allows direct command entry to be performed by the OS

Question 28

GUI stand for ? and allows ?

Answer 28

graphical user interface; it allows user-friendly desktop metaphor interface (usually mouse, keyboard, and monitor; icons represent files, programs, actions, etc.)

Question 29

application programmers typically use ? rather than directly invoking system calls

Answer 29

an API

Question 30

Android uses the ? virtual machine to run Java programs

Answer 30

Dalvik

Question 31

does C use classes and objects?

Answer 31

no

Question 32

pointer

Answer 32

a variable whose value is the address of another variable