PATH
InstallDriverFromDisk locates a file in the Extensions folder, verifies that the file contains a native driver, and loads and installs the driver.
OSErr InstallDriverFromDisk(
Ptr theDriverName,
RegEntryIDPtr theDevice,
UnitNumber theBeginningUnit,
UnitNumber theEndingUnit,
DriverRefNum *theRefNum);
InstallDriverFromDisk installs a driver that is located on disk anywhere within the specified unit number range of the unit table and invokes the driver's Initialize command, passing the RegEntryIDPtr value to it. The driver's initialization code must return noErr for InstallDriverFromDisk to complete successfully. This function returns the driver's refNum value but it does not open the driver.
If the unit table is filled throughout the range from beginningUnit to the value returned by HighestUnitNumber, and the table has not already grown to its maximum size, it can expand to accept the new driver. To use this feature, set endingUnit larger than the value returned by the HighestUnitNumber function.
InstallDriverFromDisk uses GetDriverMemoryFragment to load the driver, which then calls SetDriverClosureMemory to hold the driver's closure memory.