Speed of Virtual Memory versus RAM

Subscriber Rolf wrote to ask about the speed differences between hard drive "virtual memory" and RAM memory chips:

Hello Mr. Stockdale,

Since you actively solicit questions in your newsletter I can therefore feel like I'm not imposing too much of your daily schedule to answer a question or two from those of us (like myself) who don't have much computer savvy. As for me, well, I have more questions than you'd ever have time for; but for now I'll settle for one question, and I thank you in advance for taking time for a reply. My question is this -

Kindly explain in as simple terms as you can why free or clear space on hard drives can't act as readily or responsively in lieu of RAM. In other words ... the so-called 'virtual' RAM. I've read in a few separate places that while a computer can use this virtual RAM, it doesn't do it as efficiently as more available RAM chips, and that it is generally slower. Why can't this virtual RAM process, then release data as quickly as normal RAM? Thank you. Rolf
+++++++++++> The Irish Viking <+++++++++++++++++++

In four words: mechanical versus electronic speeds.

Any value in RAM can be accessed extremely quickly, on the order of 0.000 000 01 seconds.

Hard drives rotate and have read heads that have to move, once the read head is at the right distance from the center of the drive, the particular piece of data has to rotate into place to be read. The 250GB Western Digital IDE drive has a Read Seek Time of 8.9 milliseconds (8.9 thousandths of a second). The average latency is 4.2 milliseconds (the average delay for the data to rotate into place to be read).

To access any particular piece of data, a hard drive takes about 0.013 seconds (13 milliseconds).

To access any particular piece of data, RAM takes about 0.000 000 01 seconds.

So, when you try to "fake RAM" using hard drive space, it gets S L O W E R.

If Windows is beating your hard drive to death -- if your computer is running slow because it's swapping memory (RAM) to virtual memory (hard drive pretending to be RAM) -- you need to add more memory.

If you can't add more memory, it's time to reduce the number of programs you're running or to upgrade your computer.

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