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1. Dear students get fully solved assignments
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(SPRING 2015 ASSIGNMENT
PROGRAM BCA (REVISED FALL 2012)
SEMESTER 2
SUBJECT CODE & NAME BCA2010 – OPERATING SYSTEM
CREDIT 2
BK ID B1405
MAX.MARKS 60
Note: Answer all questions. Kindly note that answers for 10 marks questions should be
approximately of 400 words. Each question is followed by evaluation scheme.
1. Differentiate between Simple Batch Operating Systems and Timesharing Operating Systems.
Answer : Batch Operating System:
In earlycomputersystems,the userdidnotinteractdirectlywiththe computersystem.The dataand
programswere firstprepared on the input media such as punched cards or punched tape. The data
and programspreparedonthe punchedtape or punched cards were referred to as jobs. These jobs
were submitted to the computer operator. The computer operator would arrange the jobs into
propersequence knownasbatchesandrun the batchesthroughthe computer. The batch operating
system was used to manage and control such type of operations.
The simple batchoperatingsystemtransfersthe jobs to the processor one by one. When one job is
completed, then control is transferred to
2 Explain the different process states.
Answer : A process is a program in execution. The execution of a process must progress in a
sequential fashion. Definition of process is following.
A processwhichis Executedbythe Processhave variousStates,the State of the Processisalsocalled
as the Status of the process,The Status includes whether the Process has Executed or Whether the
processisWaitingfor Some input and output from the user and whether the Process is Waiting for
the CPU to Run the Program after the Completion of the Process.
The various States of the Process are as Followings:-
1) New State : When a user request for a Service

2. 3 Define Deadlock. Explain necessary conditions for deadlock.
Answer : A deadlock is a situation in which two computer programs sharing the same resource are
effectivelypreventingeachotherfromaccessingthe resource,resultinginboth programs ceasing to
function.The earliestcomputeroperatingsystemsranonlyone program at a time. Eventually some
operating systems offered dynamic allocation of resources. Programs could request further
allocations of resources after they had begun running. This led to the problem of the deadlock.
Coffman (1971) identified four (4) conditions that must hold simultaneously for there to be a
deadlock.
4. Differentiate between Sequential access and direct access methods.
Answer : The hypertext and hyperlink exemplify the direct-access paradigm and are a significant
improvement over the more traditional, book-based model of sequential access.
(Directaccesscan also be calledrandomaccess,because itallowsequallyeasyandfastaccess to any
randomlyselecteddestination.Somewhatlike traveling by a Star Trek transporter instead of driving
alongthe freewayandpassingthe exitsone ata time,whichiswhatyou getwithsequentialaccess.)
In a normal, physical book, the reader is supposed to read pages one by one, in the order in which
theyare providedbythe author.Formost books(fiction,atleast),itmakeslittle sense forthe reader
to turn directlypage 256 andstart readingthere.Unless,of course, that is where the reader left off
in their last reading session. Getting to page 256 in a 500-
5. Differentiate between Daisy chain bus arbitration and Priority encoded bus arbitration.
Answer : In most mini- and mainframe computer systems, a great deal of input and output occurs
betweenthe disksystemandthe processor.Itwouldbe veryinefficienttoperformthese operations
directlythroughthe processor;itismuch more efficientif such devices, which can transfer data at a
veryhighrate,place the data directlyintothe memory,or take the data directly from the processor
without direct intervention from the processor. I/O performed in this way is usually called direct
memory access, or DMA. The controller for a device employing DMA must have the capability of
generating address signals for the memory, as well as all of the memory control signals. The
processor informs the DMA controller that data is available (or is to be placed into) a block of
memory locations starting at a certain address in

3. 6. Explain LRU page replacement algorithm with example
Answer:A goodapproximationtothe optimal algorithmisbasedonthe observation that pages that
have been heavily used in the last few instructions will probably be heavily used again in the next
few. Conversely, pages that have not been used for ages will probably remain unused for a long
time. This idea suggests a realizable algorithm: when a page fault occurs, throw out the page that
has been unused for the longest time. This strategy is called LRU (Least Recently Used) paging.
Although LRU is theoretically realizable, it is not cheap. To fully implement LRU, it is necessary to
maintaina linkedlistof all pages in memory, with the most recently used page at the front and the
leastrecentlyusedpage atthe rear. The difficultyisthatthe list must be updated on every memory
reference. Finding a page in the list, deleting it,
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