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From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.ibm.pc,comp.sys.amiga
Subject: Re: OS/2 vs AmigaDOS
Summary: MMU
Message-ID: <101907@sun.Eng.Sun.COM>
Date: 28 Apr 89 22:51:30 GMT
References: <2134@iitmax.IIT.EDU>
Sender: news@sun.Eng.Sun.COM
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Followup-To: comp.sys.amiga
Organization: Sun Microsystems, Mountain View
Lines: 43

In article <2134@iitmax.IIT.EDU> ed@iitmax.IIT.EDU (Ed Federmeyer) writes:
> I don't really have much of an opportunity to use OS/2 or AmigaDOS, but I
> couldn't help but wonder how different the two opperating systems are?

About as different as you'd expect given the design criteria and the 
hardware. The similarities arise from the fact that when you ask the
same question, generally you get a similar answer.

> I don't understand why OS/2 uses 3 Mb of RAM (I think I read that 
> somewhere) to be usefull, while with AmigaDOS you only need 256 Kb.

To correct your thinking, the recommendation is that if you are using
Extended Addition OS/2 with Presentation Manager you need 6Mb. And on
the Amiga you only need 256K of RAM, but you put the O/S mostly in 256K
of ROM. And that is/was awfully tight. You really want 1Mb of RAM (still
with the 256K of ROM) to be comfortable. 

> What does OS/2 give you that AmigaDOS doesn't?  After all, they both 
> multitask, have graphics based interfaces, etc...  Is it maybe because 
> the 68000 assembly language is more compact than 80286 or 80386?

Good question, bad answer. For one, OS/2 gives you a full MS-DOS emulator.
Sure, you can buy one for the Amiga but it makes running Amiga programs at
the same time impossible. That can take a meg right there. Also OS/2 offers
interprocess memory protection which the Amiga doesn't (no MMU on the 68000
based models) and that certainly makes the Kernel a bit more complicated.
Also OS/2 is under a lot of time pressure and written nearly entirely in
C rather than assembler. The combination has the same effect it has on
UNIX (eg lots of code expansion). The compactness question never enters
into the picture.
 
>Please E-mail an answer to this, unless you really think everyone else
>would like to know...  Heck it might make an interesting discussion...

Actually, it could make for a boring flame fest. I've tried to get out
the facts early to prevent same, but since there are already a boatload
of messages in comp.sys.amiga I'm probably too late.


--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.
"A most excellent barbarian ... Genghis Kahn!"