Question 4) The following system uses 8KB pages (8192Bytes) All addresses are gi

Question

Question 4) The following system uses 8KB pages (8192Bytes) All addresses are given base 10 (5 marks] A) Suppose process A has the following page table: 2 marks Page Frame Invalid Invalid 12 13 14 15 16 200 19 201 202 What physical address correspond to the following virtual addresses: i) 98777 ii) 122977 ii) 131071 iv) 131072 B) Suppose process B has the following page table 2 marks Page Frame Invalid Invalid 201 28 29 30 31 50 57 149 One of the valid pages in process A is also mapped in process B. Which virtual address in process B corresponds to virtual address 123071 in process A?

Explanation / Answer

A. 1page = 8KB = 8192 bytes

1. 98777 = (8192*12) +473

So page number = 12 and offset 473

page number 12 = frame no 7

so virtual address = 7473

2. 122977 = (8192*15) +97

So page number = 15 and offset 97

page number 15 = frame no 201

so virtual address = 20197

3. 131071 = (8192*15) +8191

So page number = 15 and offset 8191

page number 15 = frame no 201

so virtual address = 2018191

4. 131072= (8192*16) +0

So page number = 16 and offset 0

page number 16 = frame no 202

so virtual address = 2020

B

virtual address in process A = 123071

= (8192*15)+191

= page no 15 and offset 191

page no 15 = frame 201

virtual address in process B = frame no 201 +offset

frame no 201 = page no 28

so corresponding virtual address in process B = 8192*28 + 191 = 229567

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