On 11/3/10 4:37 PM, Fred Cisin wrote:
  20 years would have to include "RLL" and
ESDI  (RLL has same cabling as
 ST412, but different encoding and data-rates? , ESDI cabling looks the
 same but has signal differences)
 
Biggest difference is that the data separator is on the drive so you get NRZ
data back.