Symbolic addresses: The addresses used in a source code. The variable names, constants,
and instruction labels are the basic elements of the symbolic address space.
Binding is a fancy way of saying mapping from one address space to another. In the
context of operating system, address binding takes on a special meaning - the mapping
between symbolic addresses and logical addresses.
http://web.eecs.utk.edu/~huangj/cs361/notes/memory.php
Virtual memory is a memory management technique where secondary memory can be
used as if it were a part of the main memory.
Virtual memory uses both hardware and software to enable a computer to compensate for
physical memory shortages, temporarily transferring data from random access memory
(RAM) to disk storage. Mapping chunks of memory to disk files enables a computer to treat
secondary memory as though it were main memory.
Swapping : The,basic,idea,of,swapping,is,to,treat,main,memory,as,a,
‘‘preemptable’’,resource.,A,highspeed,swapping,device,is
used,as,the,backing,storage,of,the,preempted,processes.,
DIRECTLY PROPORTIONAL: related so that one becomes larger or smaller when the other
becomes larger or smaller.
Fragmentation
Fragmentation,refers,to,the,unused,memory,that,the
memory,management,system,cannot,allocate.,
• Internal,fragmentation
Waste,of,memory,within,a,partition,,caused,by,the,difference,between,the,size,of,a,partition,
and,the process,loaded.,Severe,in,static,partitioning,schemes.
• External,fragmentation Waste,of,memory,between,partitions,,caused,by,
scattered,noncontiguous,free,space.
Severe,in,dynamic partitioning,schemes.
Compaction,(aka,relocation),is,a,technique,that,is,used, to,overcome,external,fragmentation
Paging
Physical memory is divided into a number of fixed size blocks, called frames. The logical
memory is also divided into chunks of the same size, called pages. The size of frame/page is
determined by the hardware and can be any value between 512 bytes (VAX) and 16
megabytes (MIPS 10000)! Why have such large frames? Why not?
A page table defines (maps) the base address of pages for each frame in the main
memory. The major goals of paging are to make memory allocation and swapping easier and
to reduce fragmentation. Paging also allows allocation of noncontiguous memory (i.e., pages
need not be adjacent.)
