Assignment questions for Part 2: 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
...
Assignment questions for Part 2: 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
a. Use the best-fit algorithm to indicate which memory blocks are allocated to each of
the four arriving jobs.b. 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:
a. How many pages are needed to store the entire job?
b. 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
a. 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 eachpage fault with an asterisk (*). Then compute the failure and success ratios.
b. 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.c. What general statement can you make from this example? Explain your answer.
Answer: FIFO page removal algorithm remove the pages which has been in the for the
longest time. This example shows how FIFO works. The high failure rate is because of
limited space of memory.
[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]
a) Draw a Gantt chart to illustrate the order that these processes will run, assuming the scheduling
algorithm, Shortest Remaining Time Next.b) 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 04 13
2 2 4 00 04
3 5 10 19 294 6 8 10 18
5 10 3 03 06
Average
5. Given the following information:
Job Arrival
Time
CPU
Cycle
A 0 15
B 2 2
C 3 14
D 6 10
E 9 1
Calculate the start time and finish time for each of the five jobs using each of the following
scheduling algorithms (note: show how you arrive at the answer using Gantt chart). a. SJN
b. Round robin (using a time quantum of 5, but ignore the time required for context
switching and natural wait)
Job Arrival
Time
CPU
Cycle
SJN RR
A 0 15 Start: 0
Finish: 15
Start: 0
Finish: 33
B 2 2 Start: 15
Finish: 17
Start: 5
Finish: 7C 3 14 Start: 17
Finish: 31
Start: 7
Finish: 42
D 6 10 Start: 31
Finish: 41
Start: 17
Finish: 38
E 9 1 Start: 41
Finish: 42
Start: 22
Finish: 23
[2.5*2=5 marks]
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