Re: Partitions

[David Mitchell <nospam [at] fdgroup.co.uk>]

> > Partions etc are not a feature of the hard drive - they are an artifact
> > of DOS. All PC BIOS's are written to expect the first few sectors on the
> > disk to contain the MDR and the boot block etc. If they cant find it
> > they can't boot, and so can't load the OS of your choice.
> >
> Hmmm... Ok, if that is the case, why is Linux, (a different OS as
> far as I can tell) restricted to the DOS partition format?

Okay, in slighly more detail:

hard-coded into the BIOS of all known PCs is a bit of code that makes
some basic assumptions of about what is contained in the first few sectors of
the boot disk - essentially the details of the boot block (*).
This piece of code is executed *before* anything has been read off disk,
or any boot block loaded, or any assumptions have been made about what
OS you're running.
This BIOS code was originally designed around the DOS definiton of
how things should be boot and be partioned.

Any OS that wants to to be bootable off PC hardware, be it DOS, Win 9x/NT/2K,
Linux, Solaris, SCO, FreeBSD, or ...(gosh what a lot of OSes run on PCs!),
had to abide by those few basic rules.

In addition, Microcrass products make some further assumptions about
the way they interpret those first few thinggys on the disk -chefly about
what defineds a partition.
In order to make life easier for everyone, most other OSes follow the
same conventions, in order that you can have dual-bootable systems,
without Linux corrupting the parts of the disk reserved for WinX and
vice versa.
Its possible with some OSes to tell it to ingore those conventions - which
si fine as long as you never want to run anything aprt from that one OS
on the machine.

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