I just pulled off a book from my shelf entitled "The SCSI Bus and IDE Interface, Protocols, Applications and Programming", by Friedhelm Schmidt, Addison-Wesley, 1995, ISBN 0-201-42284-0. (From the look and feel of the book, this appears to be the first time I've cracked it.)
Here's what Mr. Schmidt has to say on the origins of IDE, pp. 37-38: "The development of the IDE interface began in 1984, stimulated by the Texan computer manufacturer, Compaq. The idea was to embed the hard disk controller of an IBM AT compatible on the disk drive. Compaq contacted the controller manufacturer, Western Digital, in California. They were to produce an ST506 controller that could be mounted directly on the disk drive and connected to the system bus via a 40 pin cable. In 1985, the disk manufacturer, Imprimis, integrated this controller into its hard disk drives. Thus, the first IDE disk drive was built and installed in a Compaq computer system." "Other hard disk and computer manufacturers recognized the advantage of IDE. Not only was the increase in the cost of the disk drive negligible, but there was a great saving on the hard disk controller. Gradually, more and more IDE implementations were developed, and with them, the various deviations of the industry standard." "As a consequence, a committee of the X39.2 working group of ANSI began to deal with the problems in October, 1988. As its first project, the common access method (CAM) committee put forward a suggestion for the normalization of the IDE interface. The new name for the IDE interface was ATA. At the time of writing, (February, 1993), version 3.1 of the proposed standard was the current version, and the process to make it an ANSI standard was underway." So another voice on the chicken-vs.-egg question. As an aside, I picked up a 1986 Wren II full-height manual that discussed the drive and its various interfaces. Sadly, IDE isn't one, but SCSI is referred to as "SASI Subset"; i.e. "SCSI (SASI subset)" That concurs with my observation that SCSI was initially an Apple convention. I can recall conversations about SASI vs. Apple SCSI. --Chuck
