Quiz 1 - pt. 1

Question 1

Operating System:

Answer 1

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

Question 2

OS goals:

Answer 2

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

Question 3

Four components of a computer system:

Answer 3

1. computer hardware
2. operating system
3. system and app programs
4. users?

Question 4

user view VS system view

Answer 4

user view:

• ease of use
• doesn’t care of utilization

system view:

• maximize utilization
• protect system from malicious/non-malicious users

Question 5

kernel:

Answer 5

• resource allocator
• needs to work all the time
• initial code loaded at boot

Question 6

describe kernel mode:

Answer 6

kernel mode, as opposed to user mode, is where the system starts when it boots up. It’s where instructions are privileged, meaning they are only executable in kernel mode, and where the Operating System has unrestricted access.

Question 7

byte:

Answer 7

8 bits

Question 8

word:

Answer 8

depends on architecture:

4-bit words, 8-bit, 16-bit, 32-bit, etc.

Question 9

nibble:

Answer 9

4-bits

Question 10

Kilobyte (KB):

Answer 10

1024 bytes

2^10 bytes

Question 11

Megabyte(MB):

Answer 11

2^20 bytes

Question 12

Gigabyte(GB):

Answer 12

2^30 bytes

Question 13

Terabyte(TB):

Answer 13

2^40 bytes

Question 14

Petabyte(PB):

Answer 14

2^50 bytes

Question 15

Exabyte :

Answer 15

2^60 bytes

Question 16

Zettabyte :

Answer 16

2^70 bytes

Question 17

bootstrap program:

Answer 17

loaded at power-up or reboot:

• typically stored in ROM or EPROM, generally known as firmware
• initializes all aspects of system
• loads OS kernel and starts execution

Question 18

Computer-system organization:

Answer 18

computer-system operation:

• one or more CPUs, device controllers connect through common bus providing access to shared memory
• concurrent execution of CPUs and devices competing for memory cycles

Question 19

Device controller informs CPU that it has finished its operation by causing a(n):

Answer 19

interrupt!

Question 20

The typical computer system organization has shared memory, device controllers, and one/more CPUs connected through a common communication channel called a(n):

Answer 20

bus!

Question 21

The disk controller notices the CPU that it has fetched the data by issuing a(n):

Answer 21

interrupt!

Question 22

interrupt:

Answer 22

transfers control to the interrupt service routing generally, through the , which contains the addresses of all the service routines

Question 23

interrupt architecture must save:

Answer 23

the address of the interrupted instruction

Question 24

incoming interrupts are disabled while another interrupt is being processed to prevent:

Answer 24

a lost interrupt!

Question 25

trap:

Answer 25

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

Question 26

An operating system is ____ driven.

Answer 26

interrupt driven!

Question 27

Describe DMA:

Answer 27

Direct Memory Access:
- when a device transfers a block of data to/from its own buffer to memory without the help of the CPU

(used for high-speed I/O devices to transmit info at close to memory speeds)

Question 28

caching:

Answer 28

information in use copied from slower to faster storage temporarily.

Question 29

cache size and replacement policy:

Answer 29

when cache is full, an algorithm must choose which items to discard to make room for new ones.

Question 30

swapping:

Answer 30

if processes don’t fit in memory, swapping moves them in and out to run.

(part of Timesharing (multitasking) concept)