<P> Virtual memory is a system where all physical memory is controlled by the operating system . When a program needs memory, it requests it from the operating system . The operating system then decides what physical location to place the memory in . </P> <P> This offers several advantages . Computer programmers no longer need to worry about where the memory is physically stored or whether the user's computer will have enough memory . It also allows multiple types of memory to be used . For example, some memory can be stored in physical RAM chips while other memory is stored on a hard drive (e.g. in a swapfile), functioning as an extension of the cache hierarchy . This drastically increases the amount of memory available to programs . The operating system will place actively used memory in physical RAM, which is much faster than hard disks . When the amount of RAM is not sufficient to run all the current programs, it can result in a situation where the computer spends more time moving memory from RAM to disk and back than it does accomplishing tasks; this is known as thrashing . </P> <P> Virtual memory systems usually include protected memory, but this is not always the case . </P> <P> Protected memory is a system where each program is given an area of memory to use and is not permitted to go outside that range . Use of protected memory greatly enhances both the reliability and security of a computer system . </P>

Where is the memory stored in a laptop