CaseStudy4

A process state diagram with no transition:

.  On the diagram below, as we can see on the diagram  there is no transition from the ready state  to waiting state same with waiting to running. In the ready state to waiting state, there is no transition between them because you can only send the job in the waiting state if it came from the running state. Also, it will proceed to the waiting state if there are some interrupts and if it needs input/output request. In the waiting state to running state, there is also no transition because the process scheduler selects processes from the ready state for the CPU. Also, all jobs in the waiting list was arranged and prepared to proceed in the ready state.  In addition, only the jobs in the ready state will proceed to the running state to be run and to sidestep  the ready state would make process management impossible. In every state there would be a process to make it run before you can jump to another state but if it takes failures you go back to where you have started.

 As I understand the flow of diagram let us assign job1 to be processed.

At first job1 will go to the hold state then it will proceed to ready state which is controlled by the job scheduler-to move a job or process from one state to another,. If  job1  fails in a ready state level  because of some device failure it will go back to the hold state, and  if not, it will proceed to ready state. From the ready state, job1 will go on to the running state. If there are no interrupts occurs it will directly  proceed to the finished state. But, if it will encounter interrupts to the finished state  it will go back to the ready state and when  it fails to have the input/output request it will proceed to the waiting state. 

Computer Architecture( CaseStudy1)

Computer Architecture

 

We need to study computer architecture to select and interconnect hardware components to create computers that meet functional performance and cost goals.

Computer architecture are closely related to us as an IT students especially programmers for having a direct impact on the execution of the program.

Computer Architecture differs from Computer Organization:

Computer Architecture is the science and art of selecting and interconnecting hardware components to create computers that meet functional performance and cost goals. It refers to those attributes of the system that are visible to a programmer and have a direct impact on the execution of a program.  Computer architect coordinate of many levels of abstraction and translates business and technology drives into efficient systems for computing tasks.And view of whole design with th eimportant characteristics visible to programmers.While Computer organization defines the ways in which these components interconnected, and controlled. It is the capabilities and performance characteristics of those principal function units. Architecture can have a number of organizational implementations, and organization differs between different versions. And shows how features are implemented with the specific building blocks visible to designer or constructor,such as control signals ,interfaces,memory technology .and others

CaseStudy3

MEMORY ALLOCATION 

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

 

Case Study2

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 ...

Time sharing is a way of sharing out computer facilities between a number of people who want to use the computer at the same time. Each has a separate terminal and gets the impression that they have sole use of the computer with their own 'account'. Whereas multiprogramming is a term used to describe how a computer can run more than one application at the same time by dividing up its memory.

There are several users share the system simultaneously and with this situation it result in a various security problems such as stealing or copying of other files, this usually happen in multiprogramming and time-sharing environment, in most cases the user’s files was being over written by other users, and in this situation will lead to stealing or copying of files which greatly affects many users and because of that it create a negative impact in all other users who have their original files taken by others to engage in a multiprogramming and time-sharing environment. They believe that once your file were found by other users they will directly copy it and even without your permission that is why most of the users were very vigilant when it comes to this particular machine. And also the ability of the virus to enter in a specific files which causes the files to be damage. And other security problem is by using system resources without proper accounting basically when the system resources such as CPU and disk space are not properly accounted it causes the printer to mix output by sending data while some other user’s file is printing. This thing may result to scrambling of mix  output which cases the users to have an unfamiliar data or output and most probably the user will find it difficult in compiling his/her mixed outputs again and that will l lead him/her hard time in working with it.  

            We cannot ensure the same degree of security in a time-share machine as we have in a dedicated machine because in a time-share machine it is not safe to use all files that you’ve worked for is not permanently secured and there is a tendency that it might be copied by other users when found  .and it talks about the degree of security dedicated machine is more reliable because not all users can enter on it in return they don’t have the chance to change any files so it is so applicable to anyone.  And it cause also further damage on the files and other important programs if you don’t take it seriously. While in a dedicated machine not all files but most files were secured from being copied by the other users and because it is dedicated machine it is not virus prone so there is no need to worry with regards to virus. A dedicated machine is a computer that services one primary function or task.

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