There are a lot of issues and problems associated with the original 40-conductor IDE cable, due to its very old and not very robust
design. Unterminated flat ribbon cables have never been all that great in terms of signal
quality and dealing with reflections from the end of the cable. The warts of the old
design were tolerable while signaling speeds on the IDE/ATA interface were relatively low,
but as the speed of the interface continued to increase, the limitations of the cable were
finally too great to be ignored.

(lagi…)