Virtual Memory

by Hamish Krompaszky

how do changes in memory technology lead to innovate computer design?

As technology progresses people find new ways to get faster and better technology. They figure out ways to make the memory bigger, able to have a bigger RAM and not slow down. This then makes it a lot cheaper for the buyer because RAM Is a lot easier to buy and it is bigger. The battery is also becoming smaller and more efficient so as well as freeing up more space for memory it is now lasts a lot longer and takes less time to charge.

What is Virtual Memory?

Virtual memory is an extension of the RAM. The Page file usually has double the memory of the RAM.a Web browser and word processor into RAM simultaneously, 32 megabytes is not enough to hold it all. If there were no such thing as virtual memory, then once you filled up the available RAM your computer would have to say, "Sorry, you can not load any more applications. Please close another application to load a new one." With virtual memory, what the computer can do is look at RAM for areas that have not been used recently and copy them onto the hard disk. This frees up space in RAM to load the new application.

Because this copying happens automatically, you don't even know it is happening, and it makes your computer feel like is has unlimited RAM space even though it only has 32 megabytes installed. Because hard disk space is so much cheaper than RAM chips, it also has a nice economic benefit. ­

The read/write speed of a hard drive is much slower than RAM, and the technology of a hard drive is not geared toward accessing small pieces of data at a time. If your system has to rely too heavily on virtual memory, you will notice a significant performance drop. The key is to have enough RAM to handle everything you tend to work on simultaneously -- then, the only time you "feel" the slowness of virtual memory is is when there's a slight pause when you're changing tasks. When that's the case, virtual memory is perfect.

When it is not the case, the operating system has to constantly swap information back and forth between RAM and the hard disk. This is called thrashing, and it can make your computer feel incredibly slow.