Sdram has one notch. Depending upon the model of Sdram the number of pins it has can vary but a standard Sdram has 184 pins.
1 notch
one notch
DDR SDRAM has one notch and uses 184 pins.
By looking at the notch on the right
The notch on the right identifies the voltage used by the module.
DDR runs twice as fast as regular SDRAM, has one notch, and uses 184 pins. Instead of processing data for each beat of the system clock, as regular SDRAM does, it processes data when the beat rises and again when it falls, doubling the data rate of memory
The term DDR SDRAM refers to the phrase "double data rate synchronous dynamic random access memory". DDR SDRAM is simply a faster version of SDRAM in which data travels at a double rate. If your computer specs say that it uses DDR SDRAM it can take DDR SDRAM, but not SDRAM. DDR is 184 pins and has a notch in the bottom near the center and you will be unable to put DDR in an SDRAM mother board and also unable to put SDRAM in a DDR motherboard. Recently a new type of RAM has been introduced to market called DDR2. DDR2 is its own type and will not fit into a DDR motherboard. Hope this helps. Peace.
2.66" 200-pin SO-DIMM contains DDR2 SDRAM. One notch is near the side of the module.
DDR SDRAM uses 184 pins.
The position of the notch on the right identifies the voltage used by the module. The width of the notch <<<WRONG ANSWER! The width will be the same, but the notch can be in a different position. Please do us all a favor, if you don't know what you're talking about then don't post.
PC133 is an SDRAM standard. SDRAM is a type of RAM.