What is RAM?

RAM is Random Access Memory. RAM is the area where your computer stores programs that you are currently running and data that you are currently working on.

RAM can be contrasted with disk storage. Disk storage holds all of your programs and all of your data -- whether you are working with them or not. When you turn off your computer, the contents of RAM instantly disappear, but the contents of your disk storage remain unharmed.

RAM is also sometimes contrasted with ROM. ROM (Read Only Memory) are memory chips which have had information stored on them which cannot be changed. Your motherboard may contain some ROM chips.

Types of RAM

The two main types of RAM are:

Dynamic RAM (DRAM
Static RAM (SRAM)

Practical Effects of RAM

Upgrading your RAM is often the #1 thing which you can do to speed up your computer.

If insufficient RAM is available in your computer, modern operating systems will copy data from RAM to the hard disk. Your hard drive is much slower than RAM, so your entire computer will slow down.

What is DRAM?

DRAM is Dynamic Random Access Memory.

DRAM is the most common form of RAM.

When someone says that a computer has "one gigabyte of RAM", what they really mean is that the computer has one gigabyte of DRAM.

DRAM is called dynamic because it must constantly be refreshed or it will lose the data which it is supposed to be storing.

Refreshing DRAM consists of reading the contents from the DRAM and immediately writing them back to the DRAM.

DRAM is made up of large arrays of very small capacitors. Each of these capacitors is slowly leaking energy, and if the DRAM is not refreshed, eventually one or more of the capacitors will leak enough energy that a 1 will become a 0 and data corruption will occur.

DRAM is often contrasted with SRAM (Static RAM). SRAM is able to store data as long as power is applied to it, without needing to be refreshed. SRAM is also able to be faster than DRAM. The drawback, of course, is that SRAM is much more expensive than DRAM.

Both DRAM and SRAM lose their contents when the power to them is turned off.

What is SRAM?

SRAM is Static RAM.

SRAM is used in small amounts in computers where very fast RAM is required, such as in the L2 cache of many CPU's.

SRAM is often contrasted with DRAM (Dynamic RAM). Dynamic is much less expensive than SRAM, but is usually slower and must constantly be refreshed in order to preserve its contents.

Types of SRAM include:

Asynchronous Static RAM
Synchronous Burst Static RAM
Pipeline Burst Static RAM