Question

1. Compare logical to physical organization.

2. Compare fixed to dynamic partitioning.

3. Describe the Best-, First-, and Next-fit algorithms.

4. Describe page tables.

Answer 1

(1)

LOGICAL ORGANISATION:

(a)Processes contains various modules that is required for the execution of the program.

(b)These modules are independently compiled by the compiler during the execution.

(c)Each modules require different kind of protection and the sharing must be enabled.

(d)These all components comes under Logical Organisation.

PHYSICAL ORGANISATION:

(a)This organisation is divided into two types:

(i)Main Memory: It refers to the Random access memory which is a temporary storage device of the system.

(ii)Secondary Memory: It refers to the hard disk which is a permanent storage device of the system.

(2)

FIXED PARTITION:

(a)In this type of partitioning main memory is divided into fixed sized partitions.

(b)In this fixed sized partitions the memory is allocated to the process blocks.

(c)Fixed partitions lead to internal and external fragmentation.

DYNAMIC PARTITION:

(a)In this type of partitioning the memory is partitioned dynamically based on the size of the process blocks.

(b)Dynamic Partition will solve the problem of internal fragmentation.

(c)But dynamic partition still suffers from external fragmentation.

(3)

(a)BEST FIT : The term "best-fit" refers to allocating the block of process to the memory where the memory partition best matches with that of the size of the process block.

(b)FIRST FIT: The term "first-fit" refers to allocating the block of process to the memory where the memory partition first matches with that of the process block request.

(c)NEXT FIT: The term "next-fit " refers to allocating the block of process to the memory where the memory partition is allocated with the process block from the next partition onwards.

(4)PAGE TABLES:

(a)Page table has page table entries where each page table entry stores a page number and optional status like protection bits.

(b)When the CPU generates the logical address, it first looks into the page table to get the frame number of the memory.

(c)When it finds the frame number then it goes into memory to get the page number of the process.