Didnt ESDI come out when the IBM PS/2 announced? In a message dated 98-01-05 21:31:57 EST, you write: << Very early 80's, I think, for the ST-506. I tend to think of this as a minor variation of MFM, myself :-) The first official-type "SCSI specification" was proposed by an ANSI committee in 1984. It was almost backwards-compatible with SASI (Shugart Associates System|Storage Interface) which had been kicking around since 1978 or 1979. Mid-80's aka "ATA", clostely related to the announcement of the IBM AT... which would put it around 1985 or shortly afterwards? This wasn't really a new standard; the IDE bus interface looks exactly like a WD1002 hooked up to a MFM drive! The SA4000 and SA1000 interfaces date from the late 70's. And let's not forget the granddaddy of them all, SMD! (CDC, 1975 or so?) And SMD's immediate descendant, the MASSBUS... Tim. (shoppa(a)triumf.ca)