So, with a rudimentary understanding of data transfer, typically bits are transmitted once per full clock cycle, on the rising edge of the clock's wave. Double-pumping instead transmits twice per cycle, on both the rising and falling edge of the clock's wave. Quad-pumping goes further, by transmitting on both clock edges, and also at the peaks between them (if my understanding is wrong, please correct!).
Is there a reason that we can't always quad-pump? Is there such thing as octo-pumping, and if not, what's stopping us? What is the limiting factor? I figured these questions would all have similar answers so I folded them into just one submission, hopefully that's ok.