Functionality of Memory and Processor

Functionality of Memory and Processor

 

1. Given the following information:

Job List:			Memory Block List:
Job Number	Memory Requested		Memory Block	Memory Block Size
Job A	77K		Block 1	900K
Job B	900K		Block 2	910K
Job C	54K		Block 3	200K
Job D	801K		Block 4	300K

1. Use the best-fit algorithm to indicate which memory blocks are allocated to each of the four arriving jobs.
2. Use the first-fit algorithm to indicate which memory blocks are allocated to each of the four arriving jobs.

[2 + 2 = 4 marks]

2. If a program has 571 bytes and will be loaded into page frames of 100 bytes each, and the instruction to be used is at byte 132, answer the following questions:
   1. How many pages are needed to store the entire job?
   2. Compute the page number and exact displacement for each of the byte addresses where the data is stored. (Remember that page numbering starts at zero).

[2 + 2 = 4 marks]

 

3. Given that main memory is composed of only three-page frames for public use and that a seven-page program (with pages a, b, c, d, e, f, g) that requests pages in the following order:

a, c, a, b, a, d, a, c, b, d, e, f

1. Using the FIFO page removal algorithm, indicate the movement of the pages into and out of the available page frames (called a page trace analysis) indicating each page fault with an asterisk (*). Then compute the failure and success ratios.
2. Increase the size of memory so it contains four-page frames for public use. Using the same page requests as above and FIFO, do another page trace analysis and compute the failure and success ratios.
3. What general statement can you make from this example? Explain your answer.

[2 + 2 + 2 = 6 marks]

 

4. The table shown in part b) contains details of a set of processes that need to be scheduled by an operating system. [3+3=6 marks]
5. Draw a Gantt chart to illustrate the order that these processes will run, assuming the scheduling algorithm, Shortest Remaining Time Next.

 

1. Be sure to complete the Wait and Turnaround columns for this set of processes, including averages.

Process	Arrival time	Burst (CPU time required)	Wait	Turnaround time
1	0	9
2	2	4
3	5	10
4	6	8
5	10	3
	Avera	ge

 

 

Solution: