Buffered drive access

The API to access the physical drives (buffers) is as follows. It's implemented in DRIVE.ASM and defined in OS.INC:

LockSector
UnlockSector
ModifySector

Physical device API

The API all physical devices must implement is
as follows. The hooks are implemented in DRIVE.ASM and defined in DRIVE.INC:

open_disc_proc
close_disc_proc
check_media_proc
read_disc_proc
write_disc_proc

The virtual drive also exports the following functions that physical file systems use to register logical drives: (OS.INC)

AllocateStaticDrive
AllocateFixedDrive
AllocateDynamicDrive