BIOS versus direct access
Direct access (without BIOS):
reading and writing data directly through the hard disk controller.
the software needs to know how to address the controller and how to issue commands to it.
it needs to know the commands code for: read, write, ...
it needs also how to query the hard disk for details such as type and size.
this method is more complex, but also faster.
modern OS perform direct accesses to disks.
Access with BIOS:
slower than direct access.
but simpler, the BIOS does all the work.
the BIOS provides services to the software to communicate with the hardware.
INT 13h
andextendedINT 13h
nowadays it is only used in the boot process.
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