>>>>I want to know for example on which of the two (for example) hard disks resides drive letter 'E:'. I wish to determine this programmatically, from my own program.
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>>>There is a correlation between the drive letter and device in the HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices registry key data. However, I haven't figured out what that correlation is, nor can I find an API call to get this information. Disk Manager seems to be able to figure this out, though, so there's got to be a way to do it.
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>>DeviceIoControl()...not one I'm planning to implement in VFP without having a loaded handgun stuck in my ear...
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>Sorry to jump in but now I can't work, I'm laughing so hard...

I know one way to make you stop - try implementing DeviceIoControl() IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS using nothing but VFP and API calls...give me your weight +/- 5kg, I'll give odds on the dosage of Thorazine you'll need after a few minutes! No STRUCT or ClsHeap allowed...