16bit OS & 32bit OS

What essentially is different between a 16bit OS & 32bit OS.I know one difference as the address
pointing capacity will be more,But what exactly are other major differences that drwas a line of
distinction between 32bit OS & 16bit OS.
Secondly ,can a 64 bit OS run on a 32bit processor ?????

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Sounds a lot like homework.

As for your second question, what does the fact that a computer is a turing machine tell you? :) The implication is that a calculator processor can do anything a cray can do given enough memory.

A 16bit OS will address only 16 bit registers.  For instance on a PC that would be AX BX and so on.  Never EAX or EBX.  Those are 32bit registers. You are correct about the paging of memory.

Yes a 64bit processor can run a 32bit OS.  THink of DOS.  It is a 16 bit OS that ran on 386's.  The 386 is a 32bit processor.  Windows was Microsoft's way of charging into 32bit mode.  There are other architecture dependent issues as well.  


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I really feel the need to reply to Leimy's comments. :)

I think that its important to start by saying that the limitations of a 16 bit OS really come from the underlying hardware.

Since the 16 bit hardware didn't support things like protected mode neither would the OS. So you should look into the difference in the processors. This is in the first chapter of most OS books.

There is also the issue of memory models, not just how much you can access, but how it accessed.

Finally, the logic that since a 16 bit OS can run on a 32 processor then a 64 bit OS could run on a 32 bit processor is flawed. The problems with porting are not really the same at all.

Anyway, you really need to look at the changes in the processor, those changes dictated a lot of the inovations that appeared in PC operating systems.

Fixed the -1 problem on this question.
Escrow points corrected.

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