From: Dale and Lewis, Chapter 10 – Process Management

Paged Memory technique: A memory management technique in which processes are divided into fixed-size pages and stored in memory frames when loaded.

Frame: A fixed-size portion of a main memory that holds a process page.

Page: a fixed-size portion of a process that is stored into a memory frame:

Page-map table (PMT): The table used by the operating system to keep track of page/frame relationships.

Logical address:

· Begins as a single integer value relative to the starting point of the program.

· This address is modified into two values,

o page number –the number of times the page size divides the address

o offset - the remainder

E.G.

If the integer value of the Logical address = 2566 and page size = 1024,

Logical address ÷ page size

=2566 ÷ 1024

= 2 and 518 remainder

Interpretation: 518^th byte of page 2 of the process

So, page = 2, offset = 518

or <2, 518>

To produce a physical address:

1. look up the page in the PMT to find the frame number in which it is stored

2. multiply the frame number by the frame size and add the offset

Figure 10.7

E.G.

If process 1 is active; page size = 1024 and the logical address = <1,222>, first find the frame number of page 1 in the PMT –

· In figure 10.7, Page 1 of process 1 is in frame 12;

The corresponding physical address is therefore:

Frame no. × Page size + Offset

= 12 × 1,024 + 222

= 12,288 + 222

= 12,510

NOTE: The page number cannot be out of bounds for that process and the offset cannot be larger than the size of a frame