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From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: PC Minix/64KB limit
Message-ID: <2047@ast.cs.vu.nl>
Date: 17 Feb 89 11:01:42 GMT
References: <8752@louie.udel.EDU>
Reply-To: ast@cs.vu.nl (Andy Tanenbaum)
Organization: VU Informatica, Amsterdam
Lines: 16

In article <8752@louie.udel.EDU> ONM64%DMSWWU1A.BITNET@cunyvm.cuny.edu (Kai Henningsen) writes:
>
> I really am unable to see why
>Minix/PC can't support large Applications in the same way that
>Minix/ST does.

The problem is the brain-damaged 8088/80286 CPU.  You can only access
64K segments without doing terrible things, like making all pointers 32 bits.
This is slow, bulky, and generally unpleasant.  The whole MM has been designed
to work with a single linear address space.  The 68000 has this.  The PC
only has it if you restrict yourself to 64K I & D space.  Going to a segmented
model requires a major change to MM, which I don't want to do.  Someday,
when the normal low-end PC has a 386 in it, I can envision changing MINIX
to use 1 32-bit segment.

Andy Tanenbaum (ast@cs.vu.nl)