OS - Chapters 7-8

• Static - Binding before execution
• Dynamic - Binding at runtime

• Processor generates a logical address
• Logical address is passed through an address map
• Physical address can reference main memory

The starting memory (physical) address of the current program

• Address map
• Reloaction register addittion

• Fixed
• Variable

• Main memory is divided into physical partitions
• Partitioning happens at OS initialization
• Partitions might have different sizes

• OS assigns exact amount of space requested
• Partitions variable by length and number

• Linked list implementation
• Bitmap - Where each bit represents some portion of the memory and indicates whether it is free or occupied.

• Left shift the frame number by W bits, then add W to it
• Concatenate F and W into one number

• First Fit
• Next Fit
• Best Fit

Scan from the beginning and choose the first available block that is large enough.

• FIFO
• Least Recently Used (LRU)
• Random

Any hole can be divided into two holes. These two holes are called buddies and can be combined together to get a hole of their original size.

A fixed-size portion of virtual memory

A fixed-size portion of physical memory

A page table

• Some bits representing page address (leftmost)
• Some bits representing offset (rightmost)

2^(total number of bits in address)

The starting address of the page table of the currently running process

An entire logical component (function, module or stack)

Allows programmer to view memory as consisting of multiple address spaces or segments

• Segment Table Register
• Contains starting address of the segment table

• foo(s, w) {
•   pa = *(PTR + w) + w;
•   return pa;
• }

• Memory is broken up into segments (programmer discretion)
• Segments are broken up into fix-sized pages (same size as frames)

Page size

• Segment address
• Page (Within segment - as an offset)
• Offset (within page)

LRU > FIFO > Random