``Which technology is more difficult to test—clock-forwarding or embedded clock? The general consensus is that both are difficult but pose different challenges, with the embedded-clock approach ending up slightly more difficult. Clock-forwarding testers must accommodate the extra clock signal, but that`s not as much of a challenge as dealing with embedded-clock performance.``

http://www.reed-electronics.com/tmworld/article/CA412947.html#Why%20source-synchronous?

IMO...Moore/Fish are the first to imbed....and patent

AMD utilizes clock fowarding.....

doni