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.