Midterm

Question 1

What does the operating system do?

Answer 1

The OS abstracts the internal computer architecture and the OS manages and transparently handles all of the HW resources.

Question 2

‘Top Down’ view is associated with?

Answer 2

Abstraction (provides a clean and abstract set of resources

Question 3

‘Bottom-up’ view is associated with?

Answer 3

Management (Mangages HW resources)

Question 4

What does the Disk Driver do?

Answer 4

Deals with the hardware and provides an interface to read and write disk blocks

Question 5

The OS interacts with the device via

Answer 5

Device Driver

Question 6

What is multiplexing

Answer 6

Sharing resources in two different ways: in time and in space

Question 7

What was Generation 0 called

Answer 7

Mechanical Era

Question 8

What’s Generation 1

Answer 8

(1945-55) which consisted of the Electromechanical Relays & Vacuum Tubes Era

Question 9

What’s Generation 2

Answer 9

(1955-65) which consisted of the Transistors & Batch Systems Era

Question 10

What’s Generation 3

Answer 10

(1965-1980s) which brought solid-state IC revolution and Multiprogramming

Question 11

What’s Generation 4

Answer 11

(1980-1990) which brought “Personal” Computers.

Question 12

What’s Generation 5

Answer 12

(1990-Present) which brought Mobile Computers

Question 13

Which generation was the ENIAC created

Answer 13

Generation 1

Question 14

Where was the transistor invented?

Answer 14

AT&T’s Bell Labs.(Generation 2)

Question 15

Leading to the first class of general-purpose computers known as

Answer 15

Mainframe

Question 16

Mainframe?

Answer 16

Is a computer system that is primarily used by large organizations or institutions for bulk data processing and large-scale transactions

Question 17

What was the batch system analogous to

Answer 17

Pipelining

Question 18

Job input (Generation 2)

Answer 18

Each user’s “job” was specified by a set of input punch cards

Question 19

What did the punch cards represent

Answer 19

The cards represented the user’s ‘program’

Question 20

With the 360 what did it bring fourth

Answer 20

Multiprogramming,Dynamic Address Translation (DAT),Out-of-Order Instruction Execution

Question 21

Time-sharing

Answer 21

allows the mainframe to be ‘multiplexed’ so that multiple users could issue commands interactively while the system mostly sat idle

Question 22

The principal components of any computer system consist of

Answer 22

CPU, cache memories + MMU, Memory Subsystem (aka primary storage, I/O Devices, long term secondary storage, bus structure

Question 23

I/O is composed of?

Answer 23

a physical device and a device controller

Question 24

bus structure is?

Answer 24

connect all the computer’s subsystems.

Question 25

What's the brain of the Comptuer

Answer 25

CPU

Question 26

What does the CPU do

Answer 26

F-D-X Fetch Decode Xecute in cycles

Question 27

Two predominant types of instruction encoding and sets?

Answer 27

RISC & CISC

Question 28

The Program Counter (PC) is?

Answer 28

A register, which points to the next instruction to be fetched

Question 29

Stack Pointer (SP) ?

Answer 29

points to the top-of-stack

Question 30

Frame Pointer (FP)

Answer 30

An additional register dedicated for accessing elements within the current frame. Works with Stack pointer

Question 31

Register file (RF)

Answer 31

A set of temporary working (main) registers

Question 32

RF + SP + PC = ??

Answer 32

Execution Context

Question 33

Program Status Word (PSW)

Answer 33

This register contains the condition code bits, which are set by comparison instructions

Question 34

Execution Context

Answer 34

the internal data by which the OS is able to supervise and control the process

Question 35

Spooling?

Answer 35

Whenever a running job finished, the operating system could load a new job from the disk into the now-empty partition and run it is called what?

Question 36

Has unrestricted access to all computing resources

Answer 36

Kernal Mode

Question 37

Has very restricted access to computing resources

Answer 37

User Mode

Question 38

SMT(Simultaneous Multithreating/Hyperthreading does parrelism

Answer 38

No actually it just looks like it

Question 39

TRAP instructions are

Answer 39

The operating system calls functions

Question 40

Voluntary switches between User and Kernal modes occur...

Answer 40

often occur as a result of executing a special instruction called a 'TRAP' instruction.

Question 41

Involuntary changes in operating mode occur as a result of either

Answer 41

synchronous (aka exceptions) or asynchronous (aka Interrupts) events,

Question 42

What type event is the I/0 interupt

Answer 42

Async

Question 43

the time it takes the 'head' to slide towards the track containing the data

Answer 43

Seek Time

Question 44

The time for the 'head' to find its way to the beginning of the desired sector

Answer 44

Latency

Question 45

The amount of digital data that's moved from one place to another in a given time

Answer 45

Transfer Rate

Question 46

This counts the time from when the data is requested until its fully 'retrieved'

Answer 46

Access Time

Question 47

this is much FASTER overall access times and more energy-efficient than a HDD

Answer 47

Solid State Drive

Question 48

This is component that the CPU actually interacts with

Answer 48

Device Controller

Question 49

How does the Device controller interact with the CPU

Answer 49

As interface between the computer system (operating system) and I/O devices

Question 50

Like a 'communication system' that transfers data between system components and subsystems inside a computer

Answer 50

Bus

Question 51

address bus + data bus + control bus = ??

Answer 51

computer system

Question 52

is a program in execution?

Answer 52

Process

Question 53

Allows processes to communicate or 'sync up'

Answer 53

Interprocess Communication (IPC)

Question 54

this determines the method of how files can be structured, represented, stored and retrieved UI

Answer 54

File System

Question 55

Makes up Terminal

Answer 55

I/O + Shell

Question 56

How applications ask the OS to do things in its behalf

Answer 56

A 'system-call' Interface (I/F)

Question 57

ALL memory segments/chunks/regions which the process 'owns' and that it can read/write from/to

Answer 57

Address space

Question 58

(interrupts and halts) the current proces

Answer 58

Preempts

Question 59

A finite amount of time in which it is allowed to run

Answer 59

time quantum

Question 60

The part of the OS responsible for making these decisions

Answer 60

OS scheduler

Question 61

The OS maintains a list of all 'ready processes' in a special data structure

Answer 61

Process Table

Question 62

INIT and has a PID of

Answer 62

1

Question 63

Is the 'view' that each process has about its address space

Answer 63

Virtual memory

Question 64

an abstraction of data and/or devices, as well as its representation and device-dependent details

Answer 64

File

Question 65

UID

Answer 65

User ID

Question 66

UID is

Answer 66

a person who has access to a system

Question 67

GID stands for

Answer 67

Group ID

Question 68

GID is

Answer 68

A collection of files that are associated with each other

Question 69

PPID stands for

Answer 69

Parent Process ID

Question 70

What does a process always have

Answer 70

PPID and PID

Question 71

PID is

Answer 71

Process ID

Question 72

$ cat < myfile.txt | sort > myfile_sortex.txt is an example of

Answer 72

command pipeline

Question 73

consists of a series of 'wrapper functions' (written in C) that contain architecture-dependent assembly

Answer 73

System-call interface (SCI).

Question 74

This kernel runs the entire OS as a single program in kernel mode in a singe address space

Answer 74

monolithic kernel.

Question 75

this kernel attempts to place as little as possible in the kernel

Answer 75

microkernel

Question 76

The microkernel

Answer 76

pushes as much as it can out into 'userland'.

Question 77

The layer kernel

Answer 77

breaks up the operating system into different layers and retains much more control on the system

Question 78

This model distinguishes between two types of process client processes and server processes.

Answer 78

Client-server Model

Question 79

This kernel allocates direct H/W resources to programs. Manages allocated resources to prevent conflicts

Answer 79

Exokernel

Question 80

What does fork() do

Answer 80

Create a new process

Question 81

When a child process terminates normally it becomes a

Answer 81

Zombie

Question 82

single sequential flow of activities being executed in a processis called?

Answer 82

Thread

Question 83

switching from one program to another

Answer 83

Context Switch

Question 84

What is N:1 Implementation

Answer 84

Single kernel thread is available to work on behalf of each user process

Question 85

What is 1:1 Implementation

Answer 85

One user-space thread assigned Kernel resource

Question 86

What is N:M Implementation

Answer 86

Each kernel resource can be associated with multiple user-level threads

Question 87

Scheduler Activations is an example of

Answer 87

is an example of "many-to-many" N:M (Hybrid) kernel-mapping implementation.

Question 88

Scheduler Activation is

Answer 88

provide kernel-level thread functionality with user-level thread flexibility and performance

Question 89

The signal that is given to the thread library From kernel-space to user-space

Answer 89

Upcall

Question 90

The arrival of a message causes the system to create a new thread to handle the message is called

Answer 90

Pop Up Thread

Question 91

create_global()

Answer 91

Creates a global variable that will be stored by way of a 'pointer' in the heap

Question 92

set_global()

Answer 92

To set its value.

Question 93

thread-local globals

Answer 93

'global' variables whose 'scope' is limited to the thread.

Question 94

read_global()

Answer 94

To obtain the pointer of the global var

Question 95

multiple invocations of the procedure can safely be carried out is this type of function

Answer 95

Reentrant

Question 96

when only ONE line of execution can be within the procedure is this type of function

Answer 96

Non-reentrant

Question 97

A situation that can occur when a low-priority task is holding a resource such as a semaphore for which a higher-priority task is waiting

Answer 97

priority inversion problem

Question 98

'integer variable' to count the number of pending 'wake-ups' for future use

Answer 98

semaphore

Question 99

a synchronization mechanism that has two states 'locked' (1) or 'unlocked' (0)

Answer 99

mutex

Question 100

This method of interprocess communication uses two primitives, send and receive

Answer 100

Message Passing

Question 101

A block at the end of a phase to make all processes wait until all processes are done

Answer 101

Barrier

Question 102

This type of resource can be ‘forcibly’ taken away from the process with no ill effects

Answer 102

Preemptible

Question 103

This type of resource CANNOT be taken away safely w/o causing some potential failure.

Answer 103

Non-preemptible

Question 104

This is when no process can can operate due to a shared resource not being available

Answer 104

Deadlock

Question 105

Conditions for Resource Deadlock

Answer 105

1. Mutal Exclusion 2. Hold-and-Wait 3. No-preemption 4. Circular Wait Condition

Question 106

Do all four conditions for deadlock need to be present for a deadlock to occur

Answer 106

If one item is absent, NO resource deadlock is possible.

Question 107

What algorithm just tells you to ignore the problem

Answer 107

The Ostrich Algorithm

Question 108

What ways can the OS recover after the detection of a deadlock

Answer 108

1. Preemption 2. Recovery by voluntarily being ‘nice’ 3. Recovery through ‘Rollback’ 4. Process Killing

Question 109

What is 'Rollback'

Answer 109

‘checkpoint’ mechanism for processes which writes information about a process on a file so that it can be restarted again

Question 110

When to Look for Deadlocks?

Answer 110

Keep an ‘eye’ on CPU utilization and check when it falls below a certain threshold.