A page-replacement algorithm should minimize the number of page faults. We can achieve this minimization by distributing heavily used pages evenly over all of memory, rather than having them compete for a small number of page frames. We can associate with each page frame a counter of the number of pages associated with that frame. Then, to replace a page, we can search for the page frame with the smallest counter.

a. Define a page-replacement algorithm using this basic idea. Specifically address these problems:

i. What is the initial value of the counters?
ii. When are counters increased?
iii. When are counters decreased?
iv. How is the page to be replaced selected?

b. How many page faults occur for your algorithm for the following reference string with four page frames? 1, 2,3, 4, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2.

c. What is the minimum number of page faults for an optimal page replacement strategy for the reference string in part b with four page frames?

If you think that a blank sheet of paper or a blinking cursor on the computer screen is a scary sight, you are not alone. Many writers, students, and employees find that beginning to write can be intimidating. When faced with a blank page, however, experienced writers remind themselves that writing, like other everyday activities, is a process. Every process, from writing to cooking to bike riding to learning to use a new cell phone will get significantly easier with practice.

Just as you need a recipe, ingredients, and proper tools to cook a delicious meal, you also need a plan, resources, and adequate time to create a good written composition. In other words, writing is a process that requires steps and strategies to accomplish your goals.

These are the five steps in the writing process:

Prewriting

Outlining the structure of ideas

Writing a rough draft

Revising

Editing

Effective writing can be simply described as good ideas that are expressed well and arranged in the proper order. This chapter will give you the chance to work on all these important aspects of writing. Although many more prewriting strategies exist, this chapter covers six: using experience and observations, freewriting, asking questions, brainstorming, mapping, and searching the Internet. Using the strategies in this chapter can help you overcome the fear of the blank page and confidently begin the writing process

Explanation: