SDRAM or SDR SDRAM is a type of computer memory. SDR SDRAM stands for: Single Data Rate Synchronous Dynamic Random Access Memory. So what does that mean?
Dynamic Random Access Memory stands for DRAM or Dynamic RAM which is the more common memory found in a computer. The reason its synchronous dynamic RAM is because the RAM is synchronized with the processor. SDR SDRAM is often just called SD-RAM so don’t be confused by hearing both names used. SDR (Single Data Rate) just means that it can transfer one piece of data in contrast to DDR (Double Data Rate) which transfers twice as much.
How can you tell the difference between SD-RAM and the other types of RAM such as DDR RAM and DDR2 RAM? Well its simple, SD-RAM is the only current RAM that uses two notches. What this means is that the memory slots in the motherboard must have two notches so that the SD-RAM can fit into it. The picture below demonstrates that.
SDRAM or SDR (Single Data Rate) SD-RAM can accept one command and transfer one piece of data per clock cycle. Typical clock speeds were 66Mhz, 100Mhz and 133MHz and for more money 150Mhz.
Megabyte (MB) size in SDR SD-RAM varies from 8mb-512mb. The common sizes were 32mb, 64mb and 128mb. 256mb and 512mb sticks can be purchased for a little bit more. However, SD-RAM is no longer made so it has become more and more expensive to buy second hand. DDR and DDR2 RAM which are both a lot faster and better can be bought at a cheaper price.