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From: matt@inuxf.UUCP
Newsgroups: comp.os.minix
Subject: Re: Hardware Dependance
Message-ID: <229@inuxf.UUCP>
Date: Fri, 13-Feb-87 10:01:28 EST
Article-I.D.: inuxf.229
Posted: Fri Feb 13 10:01:28 1987
Date-Received: Sat, 14-Feb-87 14:30:30 EST
References: <275@ihnp3.UUCP> <459@moncol.UUCP> <2529@well.UUCP> <228@inuxf.UUCP> <4114@utcsri.UUCP>
Organization: AT&T Consumer Products, Indianapolis
Lines: 32

> > > My apologies if this is a dumb question, by why the design decision to
> > > make MINIX so hardware-dependant. Why wasn't the BIOS used? Does the
> > > BIOS not provide enough functionality? If the problem is just speed,
> > > why not write a slower version for those of us whose chips don't have
> > > the right pedigree? The hardware dependance strikes at one of the
> > > basic tentents of UNIX philosophy.
> > > Harry Henderson (freelance technical editor/writer).
> > ( --ME-- )
> > It seems to me that since MINIX was designed as an educational tool,
> > it may have been thought to be more educational to be able to see actual
> > driver code instead of a BIOS call using a software interrupt.  Not much
> > to be learned there except the inefficiencies of MSDOS lower layers :-).
> 
> I suspect the main reason BIOS was not used is that it is
> not re-entrant - at least 2.0 is not. That promptly makes
> serious UNIX stuff impossible, or at least darn dificult!
> It is probably much cleaner to start at the lowest level .
> 
> Mark Moraes.

On a little reflection this seems to be obvious.  I shot from the hip on my 
above response (the 'educational tool' theory) and was wide of the target. 
I still think my point is valid though.  A student will learn more from 
viewing driver code than a simple software interrupt.


 Matt Verner   				UUCP:  ...ihnp4!inuxc!matt
 AT&T Graphics Software Labs		AT&T:  (317) 844-4364
 Indianapolis,  IN

           "The whole point of this sentence is to clearly
             explain the point this sentence is making."