• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Memory Managment Operating Systems

Extracts from this document...


Ricki Lambert Operating systems Assignment 2 Memory Management Introduction Memory management is a control of the operating system. Memory management is the most vital part of keeping computers resources in order. Without this kind of management the computer would experience severe problems when multiple threads are to be run, and when processes are completed and memory is to be regained. The management system is therefore capable of allocating and de-allocating memory when needed by the system. When a system has too little memory it will become unstable and therefore almost unusable. The memory managing sector of the operating system will also allocate an orderly fashion for the executable files to be dealt with, this then allows for the memory management system to determine what is in the memory for optimum performance and C.P.U utilization. It must be constantly active searching through its system and deciding what parts are being used by whom and what threads and applications need to be moved in and out of the system. When the memory becomes to full there must be an application or process to free some of it. A list can be seen below of the main purposes of the memory management sector. 1. Relocation of memory 2. Allocation of memory 3. Protection of memory 4. Sharing of memory 5. ...read more.


This diagram bellow shows how a process is taken from the CPU and sent to the memory. * The relocation register will hold the value at the base address which is owned by the process * The relocation registers contents are added to each memory address before it is sent to the memory. * A process can never see the physical address - it will just manipulate the logical address It is clear to see that the register has a limit, and if the process exceeds the register limit it will result in an address fault. If the total is less than the limit it will proceed to the base and is added to the logical address. This is how new logical addresses are designed. Fixed and Dynamic Partitioning It is also possible for memory to be partitioned when it is within its stored elements. This is for efficient storage and avoids clustering of the memory system. The memory can be partitioned in two differing ways. Firstly is fixed partitioning. Fixed memory partitioning ensures that memory blocks are split up into fixed sizes. When a process is sent for execution a space is created and a new process can enter. ...read more.


This is done by assigning it a bit, 1 bit is for writing, 1 bit is for reading and another for execution. It can therefore be said that this process is similar to that of the linking process described earlier. The only difference is that the dynamic linking always had to reside somewhere within the R.A.M, this process however can allocate virtual memory. This is done by what is known as the paging table. This then gives the logical memory two identities, the first being a page number and the second would be an offset within that page. Then when a process is to be run the memory management must look up the page number and offset and extracts the pair of them. From this is can translate the two and turn it in to the physical memory location. This then allows the process to be run. Segmentation Segmentation is where memory resides in the logical address space in groups. There are many benefits to this, but the most important is the protection. Memory can be protected in its groups rather that each individual address space. This improves efficiency of the system and makes memory allocation far easier. From here the need for external fragmentation is not needed although there is an additional need for context switching. It can also be said that there is a clear separation between the user and the system. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Computer Science section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

3 star(s)

A good effort at a quite technical topic but some parts are not clear

Marked by teacher Ivor Borkin 01/04/2012

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Computer Science essays

  1. Peer reviewed

    information systems assignment 2

    4 star(s)

    * Personal information may be kept for no longer than is necessary.(Kept up to date) * Personal information may not be transmitted outside the EEA unless the individual whom it is about has consented or adequate protection is in place, for example by the use of a prescribed form of contract to govern the transmission of the data.

  2. Control Unit, Memory Unit, and Arithmetic Logic Unit. The CPU or Central Processing ...

    ==> Cache It is provided in computer systems to speed up processing and like all memory it is measured in bytes. Programs are made up of instructions. These are fetched from memory using the fetch-decode-execute cycle. The data that instructions need is also fetched from memory and some data might need to be fetched over and over again.

  1. Computer systems assignment 1

    * FDD- Floppy Disk Drive reads floppy disks. Those are little diskettes which hold up to 1.44 MB. The FDDs are not installe in new computer systems as they are replaced with more spacious USB disks.

  2. Future needs of Computer

    * Historical Reconstruction; * Information gathering; * The continuation of the current uses, updated and adapted with the changes in technology. There are also areas where the computer is needed to be used for more populist applications, they are: * In schools to introduce students to the discipline; * In

  1. Activity Based Costing system

    The costs of the two different products have been distorted because of the absorption costing system. It overstates the cost of a lamington, at the same time it understates the cost of a Danish pastry. Question 3 Explain how activity based costing could overcome the deficiencies inherent in the existing costing system.

  2. Explain why the Bloody Code was developed and ended!

    By the beginning of Queen Victoria's reign, the Bloody Code of the previous century, the 18th century, had almost disappeared. Capital punishment only remained for murderers and traitors. Transportation to Australia was at its highest in the 1830s, transportation ended in the early 1850s because of the increasing number of

  1. System Analysis The aim of the Jewellery store system is to make the work ...

    THREE VIEW OF THE SYSTEM Logical data models (LDM) Logical data models represent the abstract structure of some domain of information. They are often diagrammatic in nature and are most typically used in business processes that seek to capture things of importance to an organization and how they relate to one another.

  2. Input Output Functions of an Operating System

    It works within three modes and they are status, data and command. The operating will cycle through the states until the processes are complete. An example of this can be seen below; Above we can see that the operating system must cycle through the differing registers until the correct response is received.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work