DIMM Types

All DIMMs are DDR Dabble Data Rate.

Is DDR1. and DDR2. and DDR3. and DDR4. all SDR Synchronous Dynamic Ram?

 

Well DIMMs that are DDR Dabble Data Rate do this.
They can Send and Receive Data at the same Time on every Clock Cycle.

So DIMMs that are SDR Single Data Rate do this.
They can Send Data on a Clock Cycle and Receive Data on the next Clock Cycle.

Do I have this Right?

 

Ok I Looked on YouTube and the Video Say SDR DIMMs are Synchronous Dynamic RAM.
These Run at the CPU Speed.

But if I Look on Google it Says SDR DIMMs are Single Data Rate.
It Say it can Send Data on a Clock Cycle and Receive Data on a Clock Cycle.

So what am I not Understanding?