jbn@wdl1.UUCP (John B. Nagle) (06/13/84)
First off, of course you don't do it while any file system on the volume is mounted. There is a bit defined in the hardware interface between the drive and controller for all SMD-type drives which is set whenever the pack is changed and remains set until cleared by the controller. The idea is that the software should thus be able to notice a pack change and take care of any housekeeping required. In RP06 and RM05 type removables, this bit just sets a bit in one of the device registers, which UNIX ignores. But the newer drives or drivers might do something with it. Another little-known feature of the SMD interface - you can stop the drive under program control. Generally not useful in the UNIX environment, though.