Why does a computer need RAM? What does it do?
Before RAM had such wide-spread usage, two of the most important parts of a computer were the microprocessor (CPU) and storage (Hard Disk, or in many cases, just a Floppy Drive). However, microprocessors were much faster, and could not reasonably operate near their full potential because they had to 'wait' for the downright sluggish storage drive to send it data.
Random Access Memory (RAM) acts as a high speed middleman, providing enough data from the hard disk for microprocessor to use at any given time without making it wait.
Modern PC's have up to 4 levels of middlemen that exchange data with each other:
1) The L1 Cache - This is high speed SRAM found directly on the microprocessor, allowing instructions to be held for calculations. To conserve space and reduce cost, there is usually no more than 64 kilobytes on chip.
2) The L2 Cache - A secondary RAM area that operates at either the motherboard bus clock speed, the microprocessor clock speed, or a fraction of either. It holds used instructions or other data that will possibly be used again shortly. Most new PCs have between 128 KB- 1024 KB (1 megabyte).
3) The L3 Cache - The third cache level, and also the least used. When the microprocessor and motherboard both have L2 caches, the motherboard cache is designated L3, since its further away. It provides much the same role as the L2, but with a lower potential for performance gains. The few PCs that have an L3 cache usually have 512 KB of space available.
4) The System RAM - The largest and slowest RAM area. It stores data directly from storage devices to help the CPU keep up its speed. Today's PCs have between 32-64 MB, with numbers skyrocketing from there depending on the user.
How much System RAM do I need?
Windows 9x users should think of 32 MB as the bare minimum. Games and other intensive software will make better use of 64 MB, but for word processing and web-browsing you are safe with 32.
If you plan on using Windows NT or BeOS, 64 megabytes should be your minimum regardless of use. People using Unix variants will find their RAM needs will differ wildly depending on need.
Why do I need so much RAM?
Programs and operating systems are memory hogs now more than ever before. Windows 9X may say it will run with 8 MB out of the box, but that number increases rapidly based on other issues. Lets take a look at the load on a typical gamer outfitted system. This isn't a precise examination by any means, but it can very well happen anyway.
Base Level: 8 MB
16-bit Apps: +4 MB
DOS Apps +2 MB
CD Cache: +1 MB
Total: 15 MB (No applications loaded).
Netscape: +10 MB
NS Cache: +2 MB.
Total: 27 MB.
Obviously, having 32 MB total is going to help you out big time in cases like this. The extra free RAM saves your hard disk from unnecessary reads and writes, while providing room for extra applications to run.
What happens if I don't have enough RAM?
In Windows 9x, your computer will usually have a "swap file" - a file on your hard disk that acts like RAM. When system RAM runs out, your computer must start to use the swap file like RAM. Because a Hard Disk is many times slower than RAM, however, system performance is effected severely when it is used.
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