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From: kim@mcrware.UUCP (Kim Kempf)
Newsgroups: net.micro.68k
Subject: Re: Re: Re: Re: Info on OS9 Operating System
Message-ID: <138@mcrware.UUCP>
Date: Mon, 7-Oct-85 10:35:33 EDT
Article-I.D.: mcrware.138
Posted: Mon Oct  7 10:35:33 1985
Date-Received: Sat, 12-Oct-85 15:33:40 EDT
References: <347@wlbr.UUCP> <9500001@datacube.UUCP> <126@mcrware.UUCP> <275@graffiti.UUCP>
Organization: Microware Systems Corp., Des Moines, IA
Lines: 39

> > We are promoting OS-9 against UNIX not on VAXes, Pyramids or other high-end
> > hardware but on the lower end (under $5000).  Any system that is capable
> > of running UNIX requires 1) hard disk(s) and 2) memory management.  Both
> 
> 	1) False. HP put out a very nice little machine called the Integral
> 	   that not only doesn't need a hard disk, but doesn't really work
> 	   well with one.

That HP machine is a single-user machine.  The OS was an HP in-house
clone of UNIX.  Not even in the same class as OS-9.

> 
> 	2) True, but... I don't want to do serious work on a machine without
> 	   an MMU any more. It's so frustrating... even sickening... to watch
> 	   a lost pointer or bad copy of foocalc blow away everything & write
> 	   garbage over a:\*.*
> 
The MMU does a little more than protect memory.  It allows manipulation of a
process' logical address spaces.  In fact, the UNIX fork system call CANNOT
operate without an MMU (or some type of segment/base register allocation
scheme [ala 80*86]). 

> Why is an MMU that expensive?
> 
Not only in dollars.  In bus cycles.  Re: MC68451.

> Sure can. Xenix, Venix, and PC/IX all run without an MMU, apparently quite
> well. HPUX runs without a hard drive, and I'd use it if the Integral didn't
> have a typical Hewlett-Packard price tag. Neither seem to be necessary for
> UNIX.
Sorry.  Those machines use Intel processors with their segment register
on-chip MMUs.  In this case the MMU is free.

----------------
Kim Kempf, Microware Systems Corporation

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