Know Your Hardware: Memory (RAM)

In this computer tutorial, we are taking a look at DRAM, most commonly referred to as RAM.

RAM, or Random Access Memory, is one of the types of storage in our computers... And actually what we are discussing here is DRAM, or Dynamic Random Access Memory as that it what we most commonly refer to as just RAM.

DRAM is a form of volatile memory, which means that it loses all memory when power is lost. This is due to the fact that DRAM operates by storing data in capacitors which can either be charged or not charged (0 or 1). These capacitors leak charge, and hence need to be refreshed, which is why it is dynamic.

Modern DRAM is actually not random access as it reads data in bursts , but the name stuck. The fact that it has no moving components, we can still call it random I would say, as data does not have to be accessed sequentially like in a traditional hard drive.

RAM is extremely fast since it has no moving parts, with a worst case performance of constant time!

Today's most common variations of RAM are DDR(1), DDR2, and DDR3. The major differences between the generations are voltage requirements, peak performance, and number of pins. Needless to say, neither are backwards compatible.

What is RAM for?

The computer stores running applications in RAM rather than on the hard drive. Why? The CPU performs instructions at an extremely fast rate and the hard drive is simply too slow to pass data to and from the CPU in a reasonable manner. RAM on the other hand is extremely fast, with virtually no seek time, and it is able to transfer data to and from the CPU in a much more reasonable fashion!