How many notches do DDR RAM sticks have?

[meth]

I don't know if DDR RAM sticks come in different physical sizes. The
one that I've seen has only one notch around the middle. Do they also
come with two notches like DRAM sticks do?

And do RAMBUS sticks always have two notches around the middle?

 

[John Doe]

I don't know if DDR RAM sticks come in different physical sizes.
The one that I've seen has only one notch around the middle. Do
they also come with two notches like DRAM sticks do?
And do RAMBUS sticks always have two notches around the middle?

A stick of DDR RAM has one notch off-center.

http://images10.newegg.com/NeweggImage/productimage/20-145-403-02.JPG

A stick of RAMBUS RAM has two notches near center.

http://images10.newegg.com/NeweggImage/productimage/20-147-005-01.JPG