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Random Access Memory - Types of Memory

written by: Ashwin Satyanarayana•edited by: J. F. Amprimoz•updated: 6/6/2009

Upgrading your computer by adding more memory (RAM) is never possible if you didn't know what types of Memory exist. If you knew a DDR from a DDR2, matters would be that simple for you, wouldn't it? So what are the different types of Memory? Read on to know more.

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    The Evolution of RAM

    As computers evolved, so did the RAM. Over the years, we have seen a lot of improvement in the memory chips being made and the types of memory available. Knowledge of this is mandatory if you ever wanted to deal with these things on your own. There are specific memory designs each with their advantages and disadvantages, but you’d do well to have a basic idea as to what exists.

    1. FPM (Fast Page Mode): This was the kind of memory that used to come with one of those earliest Intel x86 processors. This kind of memory is slower because as it seeks to find the bits at their respective addresses, it waits until the memory controller reads each bit. It’s often considered to be just DRAM.
    2. EDO (Extended Data Out): This Memory is faster because of the way it searches for the bits in question. It seeks bits, finds them and moves on without waiting for the memory controller to read the bit in its entirety.
    3. SDRAM (Synchronous DRAM): The “synchronous" here comes from the fact that this type of memory is synchronized with the clock speeds of the CPU such that this memory too operates at one operation per cycle.
    4. DDR SDRAM (Double Data Rate SDRAM): These modules, as the names suggest, have the capability to transfer data between the CPU and the memory itself on the double. It performs its operations when the clock cycle is about to end or begin -- the rising and falling of the clock cycles.
    5. DDR 2 SDRAM (Double Data Rate 2 SDRAM): DDR 2 is DDR on steroids. An improved version of the DDR technology. Obviously, it works faster, leaner and quieter. It also consumes less power and produces less heat while operating.
    6. RDRAM (Rambus DRAM): These modules are also called as RIMMS and have the capability to transfer about 16 bits at a time through a high-speed direct Rambus Channel. Huge amounts of data transfer also entails a lot of heat being produced so most of these modules come with aluminum heat spreaders on the printed circuit board to dissipate heat.

    For most common purposes desktops might end up using anywhere from a 72-pin SIMM (Single Inline memory module) to 240-pin DIMM (Dual Inline Memory Module). Laptops use 144-pin SODIMM (Small Outline DIMM) or a 200-pin one. Net books, the latest rage now, use 144-pin MICRODIMM (Micro DIMM).

    I know these terms are all intimidating for a beginner, but a start must be made in trying to master this knowledge, don’t you think?

RAM - Random Access Memory.

RAM is so important for a computer that it deserves a series of its own. This mini series is all about RAM -- what it is, how it works, how it fits into the overall scheme of things and the various types of RAM. It will also cover the upgrade information that you might find useful
  1. Random Access Memory - How Computer Memory Works?
  2. Random Access Memory - How Much Memory Do You Need?
  3. Random Access Memory - How to Add More Memory
  4. Random Access Memory - Types of Memory