Job and Process Status

Using the process state diagram, explain why there is no transition:

• ·         From the READY to WAITING.
• ·         From the WAITING to RUNNING.

We can somehow describe the flow of the diagram by identifying the specific duties of its “States” in the process management. When a particular job is formed it will be engaged in the “Hold State”. The “Holding” queue will then pass on a job scheduler before reaching the “Ready State”. The “Ready” queue will move to the “Running State”. The “Running” queue will be checked if there will be an interrupt or an I/O request. If there are, it will be brought to the “Waiting State”. “Waiting” queue will send signals to the “Ready State” to continue the process and it will be then process again. But if there are non, then the “Running” queue will proceed to another “Job Scheduler” before making into the “finished”. 

Transition is the process through which an existing circumstance, condition, or relationship (real or imagined) is acted on in a manner that produces a new and different circumstance or condition.

From the READY to WAITING.

            I will explain this particular situation by giving an appropriate example. Let just say that job X will be the one that will be process based on the diagram.

            When job X is in the “Ready State” it must first passed the job scheduler. The job scheduler will be the one that will allow a particular job (such as job X) to be process and move to the “Ready State”. The “Ready” queue will soon make use of the CPU (Central Processing Unit) then after that the particular job (job X) will be move on the “Running State” but remember not all job can successfully passed the “Running State” most likely an interrupt will appear. An interrupt on the “Running” queue will be issued on the “Ready State”.

 But if happen that the “Running” queue will be waiting for a device (such as an I/O request) in order to work it will eventually brought to the “Waiting State”. And that how a job processed from the “Ready” to “Waiting State”. As you can observe, no transition happen because the system has been divided on its specific duties in the process management which allows the operation of system to perform accountably.

From the WAITING to RUNNING.

            When job X is supposedly in the “Waiting State” it will release signals to the “Ready State” to continue the processing of the given job. The “Ready State” will recognize the signals and so the “Waiting” queue (job X) will be back then on the “Ready State”. This is because, all incoming jobs in system must go primarily into the “Ready state” and jobs can only enter the “Running state” by passing through the “Ready state”. Shifting directly from “Waiting” to “Running State” without passing through “Ready State” will cause error in the processing of jobs.

            When the “Ready” queue (job X) is set it will directly go to the “Running State”. The “Running” queue waits for any interrupt. If no interrupt or I/O request appears it will then go through another “Job Scheduler” before reaching the “Finished” which is the end of the process. Still no transition has been made because there is no manner that produces a new and different circumstance or condition in process management.   

Fixed Partition

Load the following jobs into memory using fixed partition following a certain memory allocation method (a. best-fit, b. first-fit, c. worst-fit).

Best Fit

 

First Fit

Worst Fit

 

  

Dynamic and Relocatable Partition

Dynamic Partition

 

Relocatable Dynamic Partition

 

 

Security Problems with Multiprogramming and Time-Sharing Environments

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 ...

1. Stealing or copying of other files

     This usually happen in multiprogramming and time-sharing environment, in most cases the user’s files (the original owner of the files) was being over written by other users. This dilemma 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 where 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. In multiprogramming and time-sharing environment it usually happen because of the number of users which is actually connected to each other in which the virus easily transfer and spread from user to another, and if take for granted it may cause a lot more problems. But virus is easily detected by anti-computer virus so there is a small possibility that a virus can enter on your computer.

2. Using system resources (CPU, disk space) without proper accounting

     In a multiprogramming and time-sharing environment 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 lead him/her hard time in working with it.

Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine?

Definitely no, why do I say so? Firstly, because in a time-sharing machine as what I have explained earlier 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.

            Secondly, it is virus prone. In most cases virus-spread is vulnerable most especially when there are lots of users on that time share machine. It may cause 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 other users and because it is dedicated machine it is not virus prone so there is no need to worry with regards to virus.

            And lastly, when we talk 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 applicable to anyone. Even though time-sharing machine is very helpful because you work with other users or other people but when it comes to the degree of security dedicated machines is much more reliable.