Matt's right - since Kick 2.0 there's a single bit flag that shuts the drive up (1.x needed a real hack). I use a tiny assembler proggie to set the flags on all units it finds on startup.
For the technically interested: In order to find out whether the disk has been changed you have to move the head. The original (clicking) method moves the heads back and forth between tracks 1 & 2. The 'noclick' method keeps moving the heads outward even when they're already on track 1. 'Modern' drives know that they've reached the limit and just ignore the move command (hence no sound), while still permitting the media change check.
The reason C= kept using the original method was mainly that very old A1k drives couldn't cope with the noclick method and they weren't sure that all future drives would.
@Doppie: if the drive's still clicking with the flag set, it's likely not to handle it too well - but it's probably been doing it for years... :-)
I'm still on 3.1, so maybe 3.9 unclicks with another method (it's probably possible to step the heads up and down again so quickly that no movement actually takes place - but it might be hearable).
