This RAM, That RAM....which is which?
RAM, otherwise known as Random Access Memory, can be one of the most confusing parts of the computer to deal with. With so many variations of memory on the market today, how do you know which one to consider? Which type of RAM is best for you?
This article briefly explains the different assortment of RAM types available on the market today. SDRAM, DDR SDRAM, EDO, FPM and a few others are explained, hopefully relieving the confusion that is on many people's minds concerning which RAM is which?
SIMM, RIMMs, DIMMs, too many -IMMs for me to handle, but what exactly do each of these memory types do? SIMM, which stands for Single In-line Memory Module, are soldered onto a modular PCB (Printed Circuit Board) generally referred to as a 'stick'. This "stick of RAM" goes into the socket on the system board. SIMMs can supply up to 32-bits of data. Most of the models used are all known as "72 pin SIMMs" which refers to the 32-bit data transfer, and coincidentally the 72-pin socket they fit into. There are also "30 pin SIMMs" which have an 8-bit data transfer and fit into 30-pin sockets. Both types of SIMM are long out of date.
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| DIMM memory module |
DIMM, Dual In-line Memory Module, are in fact a lot like SIMM's in that
they are both installed vertically into memory expansion slots. One main
differences between the two types of memory is that on a SIMM pins on opposite
sides of the board are tied together to form one electrical contact. Whereas on
a DIMM, opposite pins remain isolated to form two separate contacts. DIMMs come
in 168 pin modules and provide 64-bits of data transfer. The 168-pin DIMM module
is much longer than the 72-pin SIMMs, producing twice the speed of
transfer.
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| Rambus RIMM Module |
RIMM, Rambus Memory Module, is a trademark name for the Direct Rambus Memory Module. RIMMs also look similar to the SIMM model, but with a few distinct characteristics. A two byte-wide data channel is used resulting in a peak data transfer rate of 1.6 Gigabytes per second. This seems to heat-up the chips quite easily. In order to prevent the chips from overheating, Rambus installs "heat spreaders" on the module to protect the chips from overheating. RIMMs are available in 184-pin format.
From IMM's to other acronyms:
Now that we covered the basics of the -IMM memory category, we can get into the memory chips you are much more likely to be familiar with. Memory modules such as DRAM, SDRAM, DDR SDRAM, EDO, and FPM are more than likely the types installed in our systems today.
The question remains though, what do they do for your computer?
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