Memory Management...please help!

Hey,

I've been looking through some chapters...and came across this lot of information which I just can't seem to understand very well - and it's only chapter 1 :frown:

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Could someone please help me out and explain the following to me?

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Fragmentation of Memory

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Paging

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Segmentation

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Virtual Memory

Thanks so much in advance. Any help here would be very much appreciated :redface:

Reply 1

iceman_jondoe

sorry about the late reply...i recently revised this funily enough :smile:

. Well basically your looking at the methods of scheduling here. Basically ways of ensuring computer memory (RAM) is used as most effectively as possible. Paging is when the CPU splits a process/job into a series of equally sized pages and stores them in RAM The computer keeps as many "pages" as it can in RAM especially those needed in active programs. If there is not enough RAM then the computer will have to store some of these pages in "virtual memeory" Virtual memory is storage which has been converted to act as RAM for temporary use. E.g. some space on the hard drive would be converted to ram (virtual memory) if you have run out of RAM to store pages on. This will mean some pages will be stored on the hard drive and other active ones will be sotred in RAM. This is also known as disk threshing btw. This is often why when multitasking the computer slows down because the hard drive works at a considerably slower rate compared with the CPU and RAM. Frequently you need to defragment hard drives in order to keep pages in one particular location rather than having them all spread about the place. Segmentation is like paging except the pages are of a variable size and because the pages are of a variabel size it is slower than paging because start addresses need to be calculated etc. hope this helps