http://www.scs.stanford.edu/10wi-cs1...0judgment%20of
[Draft ATA-3 standard]
Even by the time they were running the bus @ 16MB/second, they were well aware of the problems with the original ATA standard (which really had no SI controls). See Annex C in the ATA-3 standard for a more detailed explanation.
https://inst.eecs.berkeley.edu/~cs15.../ATA5_Spec.pdf
[Draft ATA-5 standard]
Section 4.2.2 talks about UltraDMA termination, and has a much more detailed annex about signal integrity.