On Tue, 31 Oct 2006 14:10:35 -0600, tdstr
Yep. ESDI was an interface standard though, rather than a way of encoding data onto the disk surface - I'm not sure what ESDI drives used internally, but probably RLL.
The cheap (it's all relative! :-) hard disks used in PCs and other home machines back in the day normally had ST506 interfaces to the computer (or its bigger brother, ST412). ESDI and SCSI were normally used for more expensive server-clbutt machines.
Later on (as I'm sure you know) IDE came onto the scene and everything apart from SCSI died out (SCSI's still used where performance matters, but tends to be a bit expensive for 'home' machines)
You know, I don't remember that - all the dual-drive setups I've seen use a straight-through control cable and then seperate data cables (one per drive) back to the controller.
PC (as in "IBM compatible") floppy drive cables do have a twist in the cable between the drives; this means that the drive motors can be controlled seperately (and also means that the user doesn't need to change jumpers on the drives themselves), but limits the system to two drives. Most other manufacturers of computers at the time stuck to the spec, which meant that they could support four drives on the same cable (with no twist) - but at the price of not being able to control the drive motors independantly and requiring the user to change ID jumpers on every drive.
cheers
Jules