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Sheet 1 “Chapter 1”


Answer briefly without non
-
useful details the following Questions:



1.

The fundamental goal of computer systems is to execute user programs and to make solving user problems easier. Toward this go
al, computer hardware is
constructed. Draw a figure that shows the computer hardware that can be considered as the basic computing
resources, which are managed by an
Operating System
.

2.

Describe the computer hardware modules that can be considered as the basic computing resources, which are managed by an
Operating System
.

3.

The
Operating System

can be simply defined as a program t
hat acts as an intermediary between a user of a computer, and the computer hardware.
Draw a figure that show how the
Operating System

is interfaced to both users and computer hardware.


Define what is an
Operating System
?

4.

What are the Objective of teaching (Why we learn)
Operating Systems
?

5.

We can define the
Operating System

as a resource manager. Name the primarily resources it manages.

6.

What are the main differences between operating systems for mainframe computers

and personal computers?

7.

Name the functions performed by an
Operating System
.

8.

Discuss 5 (five) functions that can be performed by an
Operating System
.

9.


Discuss how can operating system can be classified?

10. Define what is
afirmware
?

11.
Distinguish among Hardware , software ,
Firmware




Part 2. Writ the Corresponding Scientific Terms :


1.
The equipment of a computer system, its processor, its storage, its I/O devices, and its

communication connections.



Part
3
. Chose (circulate,
underline) the right answer
.





1.
Peoples charged with responsibility of monitoring the operating system, as responding to
request for intervention.


*

Systems Programmers

*

Systems Administration


*

Users

*

Computer operators


*

Non of all





2.
People who set policy and interface with the operating system to ensure that those policies
are properly implemented.


*

Systems Programmers

*

Systems Administration


*

Users

*

Computer operators


*

Non of all






“Chapter 2 ”






1.

Define, compare, and contrast each of the following terms :


a.

off line,


b.

on line,


c.

real time,


d.

time sharing,


e.

interactive computing

2.

Define the essential properties of the following types of operating systems :


a.

Batch


b.

Interactive


c.

Time
-
sharing


d.

Real
-
time


e.

Distributed

3.

Name the several levels of programming.

4.

Define, compare, and contrast compilers with interpreters. When should each of them be
used?

5.

Distinguish between multiprogramming and
multiprocessing.

6.

What is spooling? How would an input spooling system designed to read punched cards
from a card reader operate?

7.

An extreme method of spooling, known as staging a tape, is to read the entire contents
of a magnetic tape onto disk bef
ore using it. Discuss the main advantage of such a
scheme.

8.

In a multiprogramming and time
-
sharing environment several users share the system
simultaneously. This situation can result in various security problems.


a.

What are two such problems?


b.

Can we ensure the same degree of security in a time
-
shared machine as we
have in a dedicated machine? Explain your answer.

9.

What are the main differences between operating systems for mainframe computers and
personal computers?

10.

Why are distributed
systems desirable?

11.

What is the main difficulty a person must overcome in writing an operating system for a
real
-
time environment ?

12.

What is the nucleus or kernel of an operating system? Why the nucleus ordinarily
maintained in primary storage?
What functions are performed by the nucleus?

13.

Compare, and contrast absolute loaders with relocating loaders.

14.

How do linkage editors differ from linkage loaders?

15.
Under what circumstances would a user be better off using a time
-
sharing system
r
ather than a personal computer or single
-
use workstation?

16.
Describe the differences between symmetric and asymmetric multiprocessing. What
are the advantages and disadvantages of multiprocessor systems?

17
. Why does the nucleus ordinary run with
interrupt disabled?

18.
Describe several techniques for implementing storage protection

19.
State the different types of storage protection against OS violation.

20.
How does the distinction between monitor mode and user mode function as a
rudimentary for
m of protection (security) system?

21
.
Define, compare, and contrast several levels of Storage Hierarchy.

22
.
In hierarchical storage systems, a certain amount of overhead is involved in moving
programs and data between its various levels of the hierarchy.

Discuss the memory
hierarchy and show why the benefits derived from such systems justify this overhead
involved

23
. When are caches useful? What problems do they solve? What problems do they
cause? If a cache can be made as large as the device it is cachi
ng for (for instance, a
cache as large as a disk) why not do so and eliminates the device?

24.
Give an example of each of the following types of interrupts :

a.

Input / Output

b.

external

c.

program check

d.

restart

e.

machine check

25
.

Explain briefly what is meant by
“ status saving “ and “CPU status restoring”

26.
Identify the three techniques used for status saving and status restoring (The
techniques in this case refer to the locations where the contents of the critical
registers/counters are stored).

27
. Assume tha
t the computer system uses the simple vectored interrupt. What
happens if an interrupt is received by the CPU while servicing a prior interrupt request
from another peripheral?

28
. What is the function of program status word (PSW)? Why might the operating

system ever want to know the current PSW?

29.
What happens to PSW when an interrupt occurs? What are different schemes that
can be used for that purpose? How we return to where we left after processing the
interrupt in each one ?

30. What is the purpose
of the command interpreter? Why is it usually separate from
the kernel?

31. Describe the techniques for handling the communications between a processor
and a channel

32. what is the major drawback of the programmed i/o transfer ?

33. Briefly explain how

the interrupt I/O overcomes the disadvantages of programmed
I/O.

34.
Name the general sequence of events in case of an interrupt I/O.

35.
Draw a figure that explains the execution path of an interrupted processor.





















38.

36.

Assume that the computer system uses the :


I )
The Simple Vectored Interrupt System.

ii)
The Hardware
-

Polled Interrupt System.

iii)
The Multilevel Priority Interrupt System.

What happens if an interrupt is received by the CPU while servicing a prior interrupt
request from another peripheral?


37. What happens in the daisy
-
chain priority interrupt, when
device 1 requests an
interrupt after device 2 has sent an interrupt request to the CPU but before the CPU
responds with the interrupt acknowledge?


38.
Consider a computer without priority interrupt hardware. Any one of many sources
can interrupt the com
puter, and any interrupt request results in storing the rectum
adders and branching to a common interrupt routine. Explain how a priority can be
established in the interrupt service program


39. Identify the three techniques used for status saving and sta
tus restoring (The techniques
in this case refer to the locations where the contents of the critical registers/counters are
stored).


40. Describe different types of stacks, which are frequently used in computers to save the
contents of the CPU status ( pr
ogram counter and others ) when the interrupt handling
subroutine procedure is initiated. Compare between them in highlighting the advantages and
disadvantages of each.






Part 2 : Writ the Corresponding Scientific Term :




1.
The translator that
translates a source program written in assembly language to an
object program in machine code.




2.
It collects the routines that have been written and translated separately (to form a
program) together into a single machine language program that can
be passed to the
loader




3.
The translator that translates a source program written in a high level language to an
object program in machine language without producing an object code.



4.
The translator that do not store the machine code image
(object programs).




5.
It can place programs in various free areas of memory. It means that its function is to
take a machine language program which was generated on the assumption that it would be
loaded at some location x, usually chosen at 0 for co
nvenience, and load it starting at
location y.




6.
The part of an Operating System that handles

Interrupts.




7.
The

most intensively used code

of the operating system, that is why
it is commonly
thought to be the entire operating system. For
that reason it is always

stored in main
memory. One of its main tasks is to
handle Interrupts


The module of an Operating System that Decide which processes are to be loaded into
primary memory when memory space becomes available.




8.
The part
of an Operating System that is responsible for creation and deletion of
directories




Part 2. Chose (circulate, underline) the right answer.




The program that translates a source program written in assembly language to an object
program in machine

language.


*

Compiler

*

Assembler


*

Interpreter

*

All of them


*

Non of all





The translator that translates a source program written in assembly language to an object
program in machine code.


*

Compiler

*

Assembler


*

Interpreter

*

All of
them


*

Non of all





It collects the routines that have been written and translated separately (to form a
program) together into a single machine language program that can be passed to the
loader.



*

Assembler

*

Compiler



*

Linker

*

Relocating
loaders



*

All of the above


Non of all



It can place programs in various free areas of memory. It means that its function is to
take a machine language program which was generated on the assumption that it would
be loaded at some location x, usually chosen at 0 for convenience, and load it star
ting at
location y.



*

Assembler

*

Compiler



*

Linker

*

Relocating loaders



*

All of the above


Non of all



protection technique implemented against operating system violation in
multiprogramming systems is don by using:


*

Boundary
registers

*

Storage protection keys


*

Supervisor mode

*

All of the them


*

Non of all





The translator that do not store the machine code image ( object programs ) is :


*

Compiler

*

Assembler


*

Interpreter

*

All of them


*

Non of all






The operating system can be defined as:


*

Resource allocator

*

Control program


*

Resource manager

*

User Interface


*

All of them


Non of all



(BIOS) basic input/output system can be classified as :


*

Firmware

*

Software


*

Hardware

*

All of
them


*

Non of all





The translators that translate a source program written in a high level language to an
object program in machine language generate relatively inefficient code and operate
quickly.



*

Optimizing Compilers

*

Quick
-
and
-
Dirty
Compilers



*

Interpreter

*

All Of them



*

Non of all





The program that translates a source program written in assembly language to an object
program in machine language.



*

Optimizing Compilers

*

Quick
-
and
-
Dirty Compilers



*

Interpreter

*

All Of them



*

Non of all






Unlimited number of Programs can be archived for theoretically infinite time in:


*


Primary Memory



*


Tertiary Memory


*


Non of all



Programs are saved in:


*

Auxiliary Memory


*

Tertiary Memory


*

Non of all



support of certain system accounting functions


*

The resident
monitor

*

Process manager


*

Memory manager

*

Dispatcher


*

Processor scheduler.

*

Non of all


The provision of mechanisms for process
communication


*

File Management

*

Memory manager


*

Process manager

*

The
core

of an OS


*

Processor scheduler.

*

Non of all


Interrupt handling.

*

The kernel of an OS

*

Process manager

*

Memory manager

*

Dispatcher

*

All of the above

*

Non of
the above






The most intensively used code of the operating system that is why it is commonly thought to
be the entire operating system. For that reason it is always stored in main memory.


*

The resident
monitor

*

The Core


*

The Kernel

*

All
of the above


*

Non of all







Chapter 3


1. What are the five major activities of an operating system in regard to process
management?

2. What are the three major activities of an operating system in regard to memory
management?

3. What are the
three major activities of an operating system in regard to secondary
-

storage management ?

4. What are the five major activities of an operating system in regard to file
management?



Part 2 : Writ the Corresponding Scientific Term :


1.
The module of
an Operating System that Decide which processes are to be loaded into primary memory when
memory space becomes available.



2.
The part of an Operating System that is responsible for creation and deletion of directories




Part
3
. Chose
(circulate, underline) the right answer.




Decide which processes are to be loaded into primary memory when memory space becomes available.

*

File Management

*

Process manager

*

Memory manager

*

Dispatcher

*

All of the above

*

Non of the above


The
creation and deletion of directories

*

File Management

*

Process manager

*

Memory manager

*

Dispatcher

*

All of the above

*

Non of the above


Keeping track of status of each location of primary memory (either allocated or unallocated ).

*

File
Management

*

Process manager

*

Main memory manager

*

Dispatcher

*

All of the above

*

Non of the above
















The support of primitives for manipulating files and directories.

*

File Management

*

Process manager

*

Memory manager

*

Dispatcher

*

All of the above

*

Non of the above



Deallocation technique when the process no longer needs memory or terminated.


*

File Management

*

Process manager


*

Main memory manager

*

Dispatcher


*

Processor scheduler.

*

Non of all


The

backup of files on stable (non volatile ) storage media


*

Process manager

*

File Management


*

Memory manager

*

Dispatcher


*

Processor scheduler.

*

Non of all









Chapter
5










1.

Consider a single processor timesharing system that

supports a large number of
interactive users. Each time a processor gets a processor the interrupting clock is set to
interrupt after the quantum expires. Assume a single quantum for.All processors on the
system.

a.
What would be the effect of setting the

quantum at a very large number of minutes ?

b.
What if the quantum were set to a very small value , say a few processor cycles?



2.

As an operating system designer, you have been commissioned to design the
process and job schedulers of a new system. You hav
e been told that the high priority
jobs should be processed as quickly as possible, but that overall system throughput is
also a major consideration. As a job scheduling scheme you have been chosen to
take all high priority jobs before considering jobs of
lower priority. In designing the
process scheduler you are considering two schemes. The first is a priority scheme
identical to the job scheduler. The second scheme first tries to run I/O bound jobs,
then "normal" jobs, then CPU bound jobs, regardless of u
ser specified priority.
Discuss the two schemes with respect to overall system goals

3.

Switching from one Process to another in multiprogramming system commonly
occurs when the process has exhausted its allotted quantum of time. What are some
other reasons a
nd/or criteria for switching process?

4.

Distinguish among the following three levels of schedulers :


a.

Job scheduler.

b.

Intermediate
-
level scheduler.

c.

Dispatcher.



5.

Which level of scheduler should make a decision on each of the following question?


a.

Which ready
process should be assigned the CPU when it next becomes available?

b.

Which of a series of waiting batch jobs that have been spooled to disk should next be
initiated?

c.

Which process should be temporarily suspended to relieve a short
-
term burden on the
CPU?

d.

Whi
ch temporarily suspended process is known to be I/O
-

bound and should be
activated to balance the multiprogramming mix?


6.

which of the following refer to ‘ static priorities ’ and state which of the following refer
to ‘ dynamic priorities ’.


a.

are easier to

implement.

b.

require less run
-
time overhead.

are more responsive to changes in a process’s environment


7.

Name the different scheduling schemes, compare of them according to the following
scheduling objectives :


a.

to be fair

b.

to maximize throughput

c.

to be
predictable

d.

to obey priorities


8.
Describe the differences among short
-
term , medium term, and long
-
term scheduling.


9.
A CPU scheduling algorithm determines an order for the execution of its scheduled
processes. Given
n
processes to be scheduled on one processor, how many possible
different schedules are there? Give a formula in terms of
n
.



10.
Define the difference between preemptive and nonpreemptive scheduling.










11.
What advantage is there in having
different time
-
quantum sizes on different

levels of a multilevel queueing system?



12.
Many CPU
-
scheduling algorithms are parameterized. For example, the

RR algorithm requires a parameter to indicate the time slice. Multilevel

feedback queues require
parameters to define the number of queues,

the scheduling algorithms for each queue, the criteria used to move

processes between queues, and so on.

These algorithms are thus really sets of algorithms (for example, the

set of RR algorithms for all time slic
es, and so on). One set of algorithms

may include another (for example, the FCFS algorithm is the RR algorithm

with an infinite time quantum).What (if any) relation holds between the

following pairs of sets of algorithms?

a. Priority and SJF

b. Multilevel
feedback queues and FCFS

c. Priority and FCFS

d. RR and SJF


13.
Suppose that a scheduling algorithm (at the level of short
-
term CPU

scheduling) favors those processes that have used the least processor

time in the recent past. Why will this algorithm favo
r I/O
-
bound programs

and yet not permanently starve CPU
-
bound programs?



B.

The following are common scheduling objectives :



a.

to be fair



b.

to maximize throughput



c.

to maximize the number of interactive users receiving acceptable response
times


ii.

d.

to be predictable



e.

to minimize overhead


iii.

f.

to balance resource utilization



g.

to achieve a balance between response and utilization


i.

h.

avoid infinite postponement


iv.

i.

to obey priorities


v.

j.

to give
preference to processes that hold key resources



k.

to give lower grade of service to high overhead process


vi.

l.

to degrade gracefully under heavy loads


Which of the preceding objective most directly applies to each of the following?




i.

If

a user has been waiting for an excessive amount of time, favor that user.



ii.

The user who runs a payroll job for a 1000
-
employee company expects the job to take
about the same amount of time each week.



iii.

The system should admit jobs to create
a mix that will keep most devices busy.



iv.

The system should favor important jobs.



v.

Important processes arrive but cannot proceed because an unimportant process is holding
the resources the important job needs.



vi.

During peak period, the
system should not collapse from the overhead. It takes to manage a
large number of processes.



Part 2. Chose (circulate, underline) the right answer.






Which process should be temporarily suspended to relieve a short
-
term burden on the CPU?



*

Job scheduler

*

Dispatcher



*

Processor scheduler.

*

Intermediate
-
level scheduler.



*

The resident monitor

*

Non of all




Which of a series of waiting batch jobs that have been spooled to disk should next be
initiated?



*

Job scheduler

*

Dispatcher



*

Processor scheduler.

*

Intermediate
-
level scheduler.



*

The resident monitor

*

Non of all




When processor should be assigned to which processes?



*

Job scheduler

*

Dispatcher



*

Processor scheduler.

*

Intermediate
-
level
scheduler.



*

The resident monitor

*

Non of all



Which ready process should be assigned the CPU when it next becomes available?



*

Job scheduler

*

Dispatcher



*

Processor scheduler

*

Intermediate
-
level scheduler.



*

The resident monitor

*

Non of all


















Part 2 : Writ the Corresponding Scientific Term :


1.

The scheduler that should
select a good job mix of I/O bound & CPU bound
jobs
to have a
system with the homogenous combination to achieve the best performance.


2.

The
scheduler that decides Which of a series of waiting batch jobs that have been spooled
to disk should next be initiated?



3.

The scheduler that decides Which process should be temporarily suspended to relieve a
short
-
term burden on the CPU?



4.

The
scheduler that selects a ready process to which the CPU is assigned when it next
becomes available?



5.





6.

It is a non
-
preemptive discipline that corrects some of the weaknesses in SJF, particularly
the excessive bias against longer jobs and the
excessive favoritism toward short new jobs.
In this discipline the priority of each process (job) is a function not only the job’s service
time but also the amount of time the job has been waiting for service.


It is the interval from the time of submissio
n of a process to the time of completion. It is
the sum of time period spent waiting to get into memory, waiting in the ready queue,
executing on the CPU, and doing I/O.




C
.

Complete the following statements using the appropriate term

:


1.

Scheduling technique is ……

…... if the user who runs a payroll job for a 1000
-
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e硰xct猠shat⁨楳ij潢⁴漠瑡ke⁡扯bt⁴he⁳ me⁡m潵nt ⁴業e⁥ach⁷eek.



2.
Scheduling technique that favors a user, when this user has been waiting for an
exc
essive amount of time,
avoids the
…………


………


The scheduling discipline could be

………… …………If all processes are treated the
same.


Scheduling technique is said to that it…………. ………… if The system should favor
important jobs.












Sheet 6 " chapter 6"



Answer briefly without non
-
useful details the following Questions
:



1.

Name the different memory management schemes.



2.

Name the different memory management schemes. For each of the memory
management schemes, describe briefly the major advantages and
drawbacks.




3.

In different techniques

of memory management the main aim is to minimize the wasted
area from memory or to use memory more efficiently, but fragmentation is one of
problems that must be overcome.

What is fragmentation?. Discuss the types of storage
fragmentation and how they occur in each of the real storage organization schemes, and
how can they be overcome?



4.




Distinguish among the following placement strategies in the main storage :



first fit



best fit



worst fit





5.
In different techniques of memory management the main aim is to minimize the wasted
area

f r om memor y or t o use memor y mor e ef f i ci ent l y. But f r agment at i on, whi ch devel ops a
l ar ge number of separ at e f r ee ar eas, i s one of t he ser i ous pr obl ems t hat must be over come:



Di scuss t he t ypes of st or age f r agment at i on



Show whi ch of t hem may occur i n each

of t he di f f er ent r eal memor y management
schemes



For each of t he r eal memor y management schemes, descr i be br i ef l y t he maj or
advant ages and dr awback s.










C.

Complete the following statements using the appropriate term

:



1.

In the
……………
…………

algorithm, the free table is kept stored by location When it is
necessary to allocate memory to a job, we start at the free area at the lowest memory
address and keep looking until we find the first free area enough for the place to fit.



2.

In different techniques of memory management the main aim is to minimize the wasted
area from memory or to use memory more efficiently, but
……… ………

is one of
problems that must be overcome.






Part 2 : Writ the Corresponding Scientific Term :





1.

Placement strategies in which the free table is stored by location. When it is
necessary to allocate memory to a new job, we scan the free area at the lowest
memory address and keep looking until we find the free area enough to fit.




2.

It is the wasted
area from memory, or the large number of separate free memory
divided into small pieces.

3.

A memory management technique in which main memory is divided into a number
of

equal
-
size frames. Each process is divided into a number of equal size parts of
the sam
e length as frames. A process is loaded by loading all of its parts into
available, not necessarily contiguous, frames.



Part 3.
Find which of the following statements are correct and which are incorrect.
Put (

) in front of the correct statement and (X) in front of the incorrect one.
Underline

the wrong words, otherwise the answer is neglected.

Note that an

incorrect

statement may have several wrong words.




1.

Best fit places the program in the first storage hole

which is large
enough to hold it. ( )



2.

First fit places the program in the first “tightest” fitting hole, i.e., the
smallest of the available storage holes large enough hold it. ( )



3.

Best fit places the

program or data piece in the largest available hole
that will hold it. ( )




4.

Best fit is a low overhead strategy. First fit is intuitively appealing to
most people. Worst fit is appealing because it avoids creating small
storage holes.

( )



5.

Best fit places the program or data piece in the largest available hole that will
hold it.

( )


6.

Best fit places the program in the first storage hole which is large enough to
hold it.

( )

7.

Best fit is a low

overhead strategy. First fit is intuitively appealing to most
people. Worst fit is appealing because it avoids creating small storage holes

( )

8.

Compaction is the method that combines all free areas together into one
contiguous area. It is
used to overcome the internal fragmentation problem.

( )





Chapter 7 “ Disk Shceduling :



Answer briefly without non
-
useful details the following Questions
:



1.


Name the different Disk scheduling disciplines, Compare briefly between
them
according to the following disk scheduling goals :

i.

Throughput

ii.

Mean Response Time

iii.

Variance.






2.


Name the main Disk Storage Selection Criteria.



C
.

Complete the following statements using the appropriate term

:


1.

……………………

is the
simplest disk scheduling technique




Part 2 : Wr
i
t
e

the Corresponding Scientific Term :




1.

The time the read / write head mechanism of a magnetic disk takes to be positioned above a
given track.




Part 1.
Find which of the following statements are
correct and which are incorrect.
Put (

) in front of the correct statement and (X) in front of the incorrect one.
Underline

the wrong words, otherwise the answer is neglected.

Note that an

incorrect

statement may have several wrong words.



1.

Throughput is d
efined as number of requests serviced per unit of time. The
objectives of disk scheduling techniques generally concentrate on minimizing the
throughput.

( )


2.

The C
-
Scan scheduling technique is like Scan scheduling technique except
that it
services only requests waiting when a particular sweep begins.
Requests arriving during a sweep are grouped together and ordered for
optimum service during the return sweep.

( )

.



3.

Access time is defined as the time required to obtain the
first byte of a
randomly located set of data. In disk drives the average access time ( for
read or write ) consists of three significant actions, namely a seek time to
locate data, a rotational delay ( latency ), and record transmission. Of these,
the la
rgest by far is normally transmission time. Therefore, optimization
techniques generally concentrate on minimizing the latency time.


( )


4.

One important measure in disk scheduling techniques is the mean of
response time. It is the
mathematical measure of how far individual items
tend to deviate from the average of items. The smaller the variance the
greater the fairness of the of disk scheduling techniques.

( )



5.

At medium to heavy loading SCAN yields the best result,
while N
-
Step SCAN
has Very small variance

( )



6.

N
-
Step SCAN avoids delays and possibly indefinite postponement by forcing arriving
requests to wait until return sweep for service.
( )