The document discusses the concept of paging in operating systems, explaining how logical addresses are translated to physical addresses through the use of page tables. It describes the division of physical memory into fixed-sized frames and logical memory into pages, as well as the process of finding free frames to load programs. This address translation scheme helps manage memory efficiently by allowing noncontiguous logical address spaces.

1. Dr.T.Revathi
Department of Computer Science
PSGCAS,Coimbatore
PAGING CONCEPT with
EXAMPLE

2. Paging
• Logical address space of a process can be noncontiguous; process is
allocated physical memory whenever the latter is available.
• Divide physical memory into fixed-sized blocks called frames (size is
power of 2, between 512 bytes and 8192 bytes).
• Divide logical memory into blocks of same size called pages.
• Keep track of all free frames.
• To run a program of size n pages, need to find n free frames and load
program.
• Set up a page table to translate logical to physical addresses.
Operating System Concepts

3. Address Translation Scheme
• Address generated by CPU is divided into:
• Page number (p) – used as an index into a page table which contains base
address of each page in physical memory.
• Page offset (d) – combined with base address to define the physical memory
address that is sent to the memory unit.
Operating System Concepts

4. Address Translation Architecture
Operating System Concepts

5. Paging Example
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6. Paging Example
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