William L. Maltby wrote:
It's not truly any relationship like that. It's just (in the old days) a device ID selected on the cable by jumpers on the drive. The "control" is nothing more than the IDE controller selecting either "0" or "1" device ID for commands and data. The drive with the matching ID responds while the other ignores.
In todays world, cable select might provide the ID assignment.
I'm not sure how "master" and "slave" came to be used in this scenario, unless it had to do with BIOS boot processes back in the old days.
Well, right you are. Scroll down to "Master and Slave Clarification":
http://en.wikipedia.org/wiki/Integrated_Drive_Electronics
I had been laboring under the impression that the 'master' drive controlled both drives on a single cable. Now I've learned the truth just in time for SATA to take over. :)