Understanding Operating System Concepts Is Essential For Writing A Comprehensive Essay. (70 Characters)

• The order form should display the order that the customer has selected. – Add a date time picker in the order form. While displaying the customer’s order the date and time should also be displayed. 
• Once the order has been made the control should be disabled to prevent the customer from ordering again before the payment has been done.
• Create a payment form with calculator design. It should have numbers from 0 to 9. The design should be of your choice. You should be able to perform addition, subtraction, multiplication and division.
• Depending on the selection made by the customer calculate the price of the LUNCH BOX and display it through a message box or dialog box.

You can add some event programming and validation for higher grades.  

Safe State

Now calculating that Po will execute or not; the need of P0 is compared with the available slot.

Need <= Available

1202<= 0222 (This is not true)

Thus, Po should wait

Now calculating that P1 will execute or not; the need of P1 is compared with the available slot.

Need <= Available

0132<= 0222 (This is true)

Thus, P1 is kept in safe state

Future calculating the work,

Work= Work + Allocation

Work (P1)= 0222+0121

            = 0343

P1 is executed

Now calculating that P2 will execute or not; the need of P2 is compared with the available slot.

Need <= Available

1102<= 0343  (This is not true)

Thus, P2 should wait

Now calculating that P3 will execute or not; the need of P3 is compared with the available slot.

Need <= Available

0220<= 0222 (This is true)

Thus, P3 is kept in safe state

Future calculating the work,

Work= Work + Allocation

Work (P3)= 0343+1210

            = 1553

P3 is executed

Now calculating that P4 will execute or not; the need of P4 is compared with the available slot.

Need <= Available

2005<= 1553 (This is not true)

Thus, P4 should wait

Now, again calculating that P0 will execute or not; the need of P0 is compared with the available slot.

Need <= Available

1202<= 1553 (This is true)

Thus, P0 is kept in safe state

Future calculating the work,

Work= Work + Allocation

Work (P0)= 1553+2012

            = 3565

P0  is executed

Now calculating that P2 will execute or not; the need of P2 is compared with the available slot.

Need <= Available

1102<= 3565 (This is true)

Thus, P2 is kept in safe state

Future calculating the work,

Work= Work + Allocation

Work (P2)= 3565+4003

            = 7568

P2 is executed

Now calculating that P4 will execute or not; the need of P4 is compared with the available slot.

Need <= Available

2003<= 7568(This is true)

Thus, P4 is kept in safe state

Future calculating the work,

Work= Work + Allocation

Work (P4)= 7568 + 1030

            = 8598

P4 is executed

Thus, the Sequence is P1 P3 P0 P2 P4

The six steps are described as follows:

A.     The value of Program counter is PC= 300(Given) Thus, the address of the first instruction is 300.This value is loaded in MAR.   B.      B. The value in location 300 is loaded in MBR. The value of Pc is incremented from 300 to 301. These two steps can be done parallel. C.       The value of MBR is loaded in IR	A.     The ADDRESS PORTION OF IR(940) is loaded into MAR B.      The value in location 940 is loaded in MBR C.      The value of MBR is loaded into AC
A.     The value of PC (301) loaded in MAR B.      The value in location 301 is loaded in MBR, PC is incremented. C.      The value of MBR is loaded in IR	A.     Address portion of IR (941) is loaded in MAR. B.      Value in location 941 is loaded in MBR C.      The old value of AC and the value of location MBR are added and the result is stored in AC
A.     Value in the PC (302) is loaded in MAR. B.      The value in location 302 is loaded into MBR, PC is incremented. C.      The value of MBR is loaded in IR	A.     Address portion of IR (941) is loaded in MAR. B.      Value in AC is loaded in MBR C.      The value in MBR is stored in location 941.

Use of MAR- It is used to hold the memory location of data so that it can be accessed whenever it is needed. It is a CPU register that stores the memory address from the data so that it can be fetched from the CPU.  

Memory Management

Use of MBR- It contains the copy of memory location and copies the data item to MBR. It act as a buffer that allows the processor and memory units to act as independent units.      

These algorithms are used to decide which page is needed to be replaced when new pages enters the system. Whenever new page enter the system and there is no memory available then page fault occurs (Lee, Bahn & Noh, 2014). Operating system then uses the existing page by replacing it with the new page. There are various page replacement algorithms that are available so that number of page faults gets reduced. The different page replacement algorithms that are available are:

 It is a simplest form of page replacement algorithm in which it keeps track of all the pages and keeps the oldest page at first position in the queue. When the queue is full and ne page enters the first page is replaced (Zhan, Zhang, Jiang, Yang, Li and Li, 2018).

Advantage and disadvantage- It is easy to understand but it is not very effective. It has a very slow process execution rate and also increases the chances of page fault (Tsai and Lei, 2017).

It is an algorithm in which the page that has less probability of being used in future is replaced. It is used to set a benchmark so that other replacement algorithm can be compared and analysed (Zhan, Zhang, Jiang, Yang, Li and Li, 2018).

Advantage and disadvantage- It is useful as it has lowest page fault rate and it never suffers from the issue of Belady’s anomaly. It is difficult to implement and need future knowledge to take any actions.

The page that is used very least is replaced with the new page. It uses the principal of locality like replacing the page which is less likely to be referenced in the near future (Tsai and Lei, 2017).

Advantage and disadvantage- It also never suffer from Belady’s anomaly and assembles full statically analysis (Wu,  Jin, Yang and Yue, 2014)

 Some of the terms are explained by considering one general human example is:

The concept of live lock is similar to deadlock; the only difference in live lock is that state of processes keeps on changing with respect to other processes (Hu, Neamtiu & Alavi, 2016). It is a case off resource starvation but it generally occurs when specific process is not progressing (Yu, Srisa-an, & Rothermel, 2017).

Example- The real life example of live lock is when two humans collide in a narrow corridor. There is a very little space for both the individuals to pass together from the corridor. But if both the individuals adjust a little by moving side the issue could be resolved (Gao & Xu, 2015). But while moving aside they end up swaying with each other without making any progress.

 It is an unwanted condition that occurs when two or more operations are performed by the system at the same time. It causes can issues as a proper sequence needs to be followed for completing the operations correctly.  Apart from that in computer system this issue arise at the time of entering commands. The wrong sequence can overwrite the commands and may cause error (Qin & Jin, 2015).

Example- A human related example that can explain this situation is condition of light switch. In offices or homes, many light switches are connected from a same celling light. Thus, irrelevant position of the switches may cause wrong output. The problem will arise when two individuals are using the switch at the same time. Thus, their actions will cancel out and no result would be obtained.

It is a situation when other the system requires the same resource at the same time. Deadlock is a condition that prevents both the user to access the resources. In terms of computer science, deadlock is a condition when two or more processes are waiting for the resource to be released by other process.