CASE STUDY 5

University of Southeastern Philippines
Institute of Computing
OPERATING SYSTEMS
Second Semester – SY 2010-2011
Name: Maria Edna Hernandez
Section: BSIT-3
Case Study #: 5
Load the following jobs into memory using fixed partition following a certain memory allocation method (a. best-fit, b. first-fit, c. worst-fit).
Memory Block Size
Block 1 50K
Block 2 200K
Block 3 70K
Block 4 115K
Block 5 15K
a. Job1 (100k) f. Job6 (6k)
turnaround: 3 turnaround: 1
b. Job2 (10k) g. Job7 (25k)
turnaround: 1 turnaround: 1
c. Job3 (35k) h. Job8 (55k)
turnaround: 2 turnaround: 2
d. Job4 (15k) i. Job9 (88k)
turnaround: 1 turnaround: 3
e. Job5 (23k) j. Job10 (100k)
turnaround: 2 turnaround: 3
*turnaround – how long it will stay in the memory.









Memory Block Size




BEST-FIT
Phase1
Block Size
Job3 (35k) 50K
Job5 (23k) 200K
Job4 (15k) 70K
Job1 (100k) 115K
Job2 (10k) 15K
Job6 (6k) waiting

Phase 2
Block Size
Job3 (35k) 50K
Job5 (23k) 200K
Job7 (25k) 70K
Job1 (100k) 115K
Job6 (6k) 15K
Job8 (55k)

Phase 3
Block Size
50K
Job9 (88k) 200K
Job8 (55k) 70K
Job1 (100k) 115K
15K
Job10(100k) waiting
Phase 4
Block Size
50K
Job9 (88k) 200K
Job8 (55k) 70K
Job10 (100k) 115K
15K

Phase 5
Block Size
50K
Job9 (88k) 200K
70K
Job10 (100k) 115K
15K

Phase 6
Block Size
50K
200K
70K
Job10 (100k) 115K
15K

Phase 7
Table empty

Worst-Fit
Phase1
Block Size
Job4 (15k) 50K
Job1 (100k) 200K
Job3 (35k) 70K
Job2 (10k) 115K
15K
Job5 (23k) waiting

Phase2
Block Size
Job6 (6k) 50K
Job1 (100k) 200K
Job3 (35k) 70K
Job5 (23k) 115K
15K
Job7 (25k) waiting

Phase3
Block Size
50K
Job1 (100k) 200K
Job7 (25k) 70K
Job5 (23k) 115K
15K
Job8 (55k) waiting
Phase 4-5
Block Size
50K
Job8 (55k) 200K
70K
Job9 (88k) 115K
15K
Job10 (100k) waiting

Phase 6
Block Size
50K
Job10 (100k) 200K
70K
Job9 (88k) 115K
15K

Phase 7-8
Block Size
50K
Job10 (100k) 200K
70K
115K
15K

Phase 9
Table empty
First-Fit
Phase 1
Block Size
Job2 (10k) 50K
Job1 (100k) 200K
Job3 (35k) 70K
Job4 (15k) 115K
15K
Job5 (23k) waiting
Phase 2
Block Size
Job5 (23k) 50K
Job1 (100k) 200K
Job3 (35k) 70K
Job6 (6k) 115K
15K
Job7 (25k) waiting

Phase 3
Block Size
Job5 (23k) 50K
Job1 (100k) 200K
Job7 (25k) 70K
Job8 (55k) 115K
15K
Job9 (88k) waiting
Phase 4
Block Size
50K
Job9 (88k) 200K
70K
Job8 (55k) 115K
15K
Job10 (100k) waiting

Phase 5-6
Block Size
50K
Job9 (88k) 200K
70K
Job10 (100k) 115K
15K
Job10 (100k) waiting

Phase 7
Block Size
50K
200K
70K
Job10 (100k) 115K
15K

Phase 8
Table empty

CASE STUDY 4

University of Southeastern Philippines
Institute of Computing
OPERATING SYSTEMS
Second Semester – SY 2010-2011
Name: Maria Edna Hernandez
Section: BSIT-3
Case Study #: 4
Load the following jobs into memory using dynamic partition and relocatable dynamic partition: (The memory size is 220k with allocated OS for 15k).
a. Job1 (100k) f. Job6 (6k)
turnaround: 3 turnaround: 1
b. Job2 (10k) g. Job7 (25k)
turnaround: 1 turnaround: 1
c. Job3 (35k) h. Job8 (55k)
turnaround: 2 turnaround: 2
d. Job4 (15k) i. Job9 (88k)
turnaround: 1 turnaround: 3
e. Job5 (23k) j. Job10 (100k)
turnaround: 2 turnaround: 3

*turnaround – how long it will stay in the memory.
*apply compaction if only if the incoming jobs has no other block to allocate that will fit their sizes.










Dynamic Partition
Phase 1
OS(15k) 15k
Job1 (100k) 110k
Job2 (10k) 15k
Job3 (35k) 80k
Job4 (15k) waiting

Phase 2
OS 15k
Job1 (100k) 110k
Job4 (15k) 15k
Job3 (35k) 80k
Job5 (23k) waiting

Phase 3
OS 15k
Job1 (100k) 110k
Job6 (6k) 15k
Job5 (23k) 80k
Job7 (27k) waiting

Phase 4
OS 15k
Job7 (27k) 110k
15k
Job5 (23k) 80k
Job8 (55k) waiting
Phase 5-6
OS 15k
Job8 (55k) 110k
15k
80k
Job9 (88k) waiting.
Phase 5 and 6 has same data in the table because there is not enough space for job 9. We need to wait for job 8 to finish its turnaround before Job9 can enter.

Phase 7-9
OS 15k
Job9 (88k) 110k
15k
80k
Job10 waiting. Same case with phases 5-6

Phase 10-12
OS 15k
Job10 (100k) 110k
15k
80k
Waiting for its turnaround to finish before having an empty table.

Phase 13
Table empty.

Relocatable Dynamic Partition

Phase 1
OS(15k) 15k
Job1 (100k) 110k
Job2 (10k) 15k
Job3 (35k) 80k
Job4 (15k) waiting

Compaction
OS(15k) 15k
Job1 (100k) 115k
Job3 (35k) 160k
Job4 (15k) 175k
Job5 (23k) 198k
Job6 (6k) 204k

Phase2
OS(15k) 15k
Job1 (100k) 115k
Job3 (35k) 160k
Job4 (15k) 175k
Job5 (23k) 198k
Job6 (6k) 204k
Job7(25k) waiting.




Compaction
OS(15k) 15k
Job1 (100k) 115k
Job5 (23k) 138k
Job7 (25k) 163k
Job8(55k) 218

Phase3
OS(15k) 15k
Job1 (100k) 115k
Job5 (23k) 138k
Job7 (25k) 163k
Job8(55k) 218
Job9 (88k) waiting

Compaction
OS (15k) 15k
Job8 (55k) 70k
Job9 (80k) 158k

Phase 4
OS (15k) 15k
Job8 (55k) 70k
Job9 (80k) 158k
Job10 (100k)




Compaction
OS (15k) 15k
Job9 (88k) 103k
Job10 (100k) 203k

Phase 5-6
OS (15k) 15k
Job9 (88k) 103k
Job10 (100k) 203k

Phase 7

OS (15k) 15k
Job10 (100k) 115k

Phase 8
Table empty

CASE STUDY 3

University of Southeastern Philippines
Institute of Computing
OPERATING SYSTEMS
Second Semester – SY 2010-2011


Name: Maria Edna Hernandez
Section: BSIT-3
Case Study #: 3

In a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems. Name at least two of these problems. Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine? Explain your answer
Two potential problems in this kind of environment are:

1) One user can copy another user's program / memory space. This could be very detrimental if, for example, an administrator was running a decryption protocol, and another user stole the decrpytion program and/or key.

2) Resource usage may not be completely controlled, and could cause deadlock for certain users. For example, if user A had resource 1 and was waiting for resource 2, and user B had resource 2 and was waiting for resource 1, deadlock would occur and neither user would be able to make progress in their program, no matter how many time slots they were allocated.

In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task. Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn. The act of reassigning a CPU from one task to another one is called a context switch. When context switches occur frequently enough the illusion of parallelism is achieved. Even on computers with more than one CPU (called multiprocessor machines), multitasking allows many more tasks to be run than there are CPUs.

One user can copy another user's program / memory space. This could be very detrimental if, for example, an administrator was running a decryption protocol, and another user stole the decryption program and/or key.
Resource usage may not be completely controlled, and could cause deadlock for certain users. For example, if user A had resource 1 and was waiting for resource 2, and user B had resource 2 and was waiting for resource 1, deadlock would occur and neither user would be able to make progress in their program, no matter how many time slots they were allocated.
In a multiprogramming and time-sharing environment,several user share the system simultaneously. This situation can result in various security problems. One user may modify the data which is required by another user. One user may use the resources but charge expenses to some anothe user.

CASE STUDY 2

University of Southeastern Philippines
Institute of Computing
OPERATING SYSTEMS
Second Semester – SY 2010-2011


Name: Maria Edna Hernandez
Section: BSIT-3
Case Study #: 2

Select two of the following professionals:
• An insurance adjuster
• A delivery person for a courier service
• A newspaper reporter
• A doctor (general practitioner)
• Manager in a supermarket
Put forward a theory about how that person might use a hand held computer in their work

I choose the doctor which is a general practitioner and the news pper reporter because they re both in line with a very busy schedule knowing that having hand held computers are useful for was scheduling of appointments and events. Doctors who used handheld computers in clinical practice seemed generally satisfied with them and reported diverse patterns of use. Users perceived that the devices helped them increase productivity and improve patient care. Barriers to use concerned the device itself and personal and perceptual constraints, with perceptual factors such as comfort with technology, preference for paper, and the impression that the devices are not easy to use somewhat difficult to overcome. Participants suggested that organisations can help promote handheld computers by providing advice on purchase, usage, training, and user support. Participants expressed concern about reliability and security of the device but were particularly concerned about dependency on the device and over-reliance as a substitute for clinical thinking. Doctors expect handheld computers to become more useful, and most seem interested in leveraging (getting the most value from) their use. Key opportunities with handheld computers included their use as a stepping stone to build doctors' comfort with other information technology and ehealth initiatives and providing point of care support that helps improve patient care.

Meanwhile for newspaper reporter, it is very useful in a way that once data is in the handheld computer it can be transferred to other devices, including desktop computers, laptops, and other handheld computers. This transfer also provides a backup of the data on the handheld computer. Lets take for examlpe that a news paper reporter is on the field taking records about what happened in a certain insident, everything the reporter might discover can be noted to the handheld computer so the reporter won’t have a hard time typing everything agian to the computer because with the use of the hand held computer they can easily transfer it thru cables, infrared beaming, modems, and in some models by wireless communication. All they have to do is simply edit it that to be printed for the newspaper.

CASE STUDY 1

University of Southeastern Philippine

Institute of Computing

OPERATING SYSTEMS

Second Semester – SY 2010-2011

Name: Maria Edna Hernandez

Section: BSIT 3

Case Study #1:

Give an example OS (Specific) for each of the following categories of OS:

1.Batch Systems

* Batch is not an operating system, but a scripting language. Batch can for example be used to create a shell for MS-DOS, to create drive mappings, et cetera.

*IBM’s OS360 is a popular batch processing system.

*Batch processing is execution of a series of programs (“jobs”) on a computer without manual intervention.

2.Interactive Systems

*Distributed interactive systems are composed of a number of components that interact, for example, by exchanging messages or by updating shared memory.

* UMLi Example (1) P. de Silva/N. Paton: User Interface Modeling in UMLi, IEEE Software 20(4) 2003, pp. 62-69 (b)

(b) UMLi user interface diagram

3. Real-time systems

*a novel software technology are called hard real-time operating systems

*The first category includes many commercial kernels (such as VRTX32, pSOS, 0S9, VxWorks, Chorus, and so on) that, for many aspects, are optimized versions of timesharing operating systems.

*In these systems, time management is realized through a real-time clock, which is used to start computations, generate alarm signals, and check timeouts on system services. Task scheduling is typically based on fixed priorities and does not consider explicit time constraints into account, such periods or deadlines.

*second category of operating systems includes the real-time extensionsof commercial timesharing systems. For instance, RT-UNIX and RT-MACH

*Represent the real-time extensions of UNIX and MACH, respectively. The advantage of this approach mainly consists in the use of standard peripheral devices and interfaces that allow to speed up the development of real-time applications and simplify portability on different hardware platforms.

4.Hybrid Systems

* A hybrid system is a dynamic system that exhibits both continuous and discrete dynamic behavior – a system that can both flow (described by a differential equation) and jump (described by a difference equation or control graph). Often, the term “hybrid dynamic system” is used, to distinguish over hybrid systems such as those that combine neural nets and fuzzy logic, or electrical and mechanical drivelines. A hybrid system has the benefit of encompassing a larger class of systems within its structure, allowing for more flexibility in modelling dynamic phenomena.

*Hybrid systems have been used to model several systems, including physical systems with impact, logic-dynamic controllers, and even Internet congestion.

* A ‘Hybrid System’ is defined as an environment consisting of both Electronic and Paper-based Records (Frequently Characterized by Handwritten Signatures Executed on Paper). A very common example of a Hybrid System is one in which the system user generates an electronic record using a computer-based system (e-batch records, analytical instruments, etc.) and then is require to sign that record as per the Predicate Rules (GLP, GMP. GCP).

5. Embedded Systems

* An embedded system is a computer system designed to perform one or a few dedicated functions often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer (PC), is designed to be flexible and to meet a wide range of end-user needs. Embedded systems control many devices in common use today

* Physically, embedded systems range from portable devices such as digital watches and MP3 Players, to large stationary installations like traffic lights, factory controllers or the systems controlling nuclear power plants. Complexity varies from low, with a single micro controller chip, to very high with multiple units, peripherals and networks mounted inside a large chasis or enclosure.