But the master drive doesn't control the slave drive. The controller controls them both -- the master drive is the one that, on the primary controller, is the bootable drive. And the one that the OS assigns the first letter/whatever designation.
The terms master/slave are wrong. If you're going to bother changing it (which I still think is overreaction -- the words master and slave are not barbs, just descriptors -- if they'd been called master and nigra, or something, I'd get it), there's no point maintaining the false relationship.
Primary and secondary is about it.