Low Level Hard Disk Access
DOS
  - 	BIOS Int 13h (need BIOS Extensions for disks above 8GB)
Windows 9x
  - 	DOS programs: like DOS, but must use volume 
lock/unlock for write access
  
- 	Win16 programs:	must call BIOS Int 13h via DPMI
  
- 	Win32 programs: 32bit to 16bit thunking to a Win16 DLL
Windows NT
  - 	DOS programs: not allowed
  
- 	Win16 programs: not allowed
  
- 	Win32 programs: CreateFile(), ReadFile(), WriteFile()
Linux/UNIX