CS 514 Advanced Operating Systems, Spring 2009 Quiz #1 on January 27, 2009 (Solutions)

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1

CS 514 Advanced Operating Systems, Spring 2009

Quiz #1 on January

2
7, 2009

(
Solutions
)


This quiz is a closed lecture
-
notes, closed textbook and close neighbor quiz. Since the way you are
expected to answer for the questions can be different for each ques
tion, please read each question
carefully before you start answering a solution for the question. Failing to follow the instruction in
each question will be considered “a wrong solution” (not as “unanswered), which is subject to a
minor penalty (as descri
bed below).


Your
Last Four Digits: ________________

(please do NOT write all of your student ID or your name)



Grade: ______


************************************************************************


(1)

What are the two primary roles of operating system
s?




The interface between human users (user applications) and the physical computer hardware.



The resource manager (government)
that manages and allocates all the available hardware resources
in your computer system
.


(2)

What is

extended machine

? Thi
s question does
not

ask how we can use extended machine. A
definition of

extended machine


is
needed.

Please answer this question using up to 40 words
.


Definition (required)
: “Extended machine” is a software (or a collection of software) that emulates
particular functionalities that are not directly provided by a physical computer system to human users
and/or user applications.


Purpose (not required: FYI)
: The primary purpose of extended machine is to let human users and
application programs run on a c
omputer system that does not support the functionalities they need.


(3)

What is

context
switching”
?


Context switching is a process of switching a processor from the currently running process to another
process.


(4)

What is

file allocation table

? Wha
t is it for (mention the most important role of FAT)?


File allocation table (as usually abbreviated as “FAT”) is
the data structure

that
keeps track of where in
a storage device each file is located
.





2

(5)

What is the primary difference between

networke
d OS


and

distributed OS
” (answer this
question
using up to 25 words
)
?


“N
etworked OS


and

distributed OS
” are same in that such OS connects multiple computer hosts in a
network, but they have the following difference:




Using a networked OS, each human u
ser still sees multiple difference computer hosts.



Using a distributed OS, each human user will not distinguish each networked host computer any
more. In stead, each user will see only them as if only one computer host.


(6)

What are the advantages in usi
ng

micro
-
kernel architecture

? What is the primary disadvantage in

micro
-
kernel architecture

?

Answer each question using up to 25 words
.




OS kernel becomes smaller (by kicking out those functions outside of the kernel).



Since some of the functions wil
l be executed in the user mode (not in the system mode), robustness
will be improved.



Novice users can perform “debugging” the bugs, by simply downloading the latest file and replace
the old by the new.


(7)

Many operating systems use

external commands

.

What is the primary difference between

external
commands


and

micro
-
kernel architecture

?


The primary difference between
external commands

and the micro
-
kernel architecture is that the
external commands are executed as the kernel mode while micro
-
kerne
l architecture execute some OS
services in the user (application mode).


(8)

Special files are not limited to interfacing to I/O devices. There are at least two more different ways to
use special files. Mention at least another example of special files (
your example should not be the one
related to accessing I/O devices).


Many different solutions are possible.
















________________________________________________________________________

CS 5
14,

Advanced Operating S
y
stems Spring 2009
, Qui
z #1, J
anuary 27, 2009
.