INT 21 - DOS 5.0 - ENABLE DRIVE
AX = 5F07h
DL = drive number (0=A:)
Return: CF clear if successful
CF set on error
AX = error code (0Fh) (see AH=59h)
Note:   simply sets the "valid" bit in the drive's CDS
SeeAlso: AX=5F08h"DOS"

See also: 2152

215F07 - DOS 5.0 - ENABLE DRIVE