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From: tim@ism780c.UUCP (Tim Smith)
Newsgroups: comp.sys.amiga,comp.sys.mac,comp.sys.m68k,comp.sys.misc
Subject: Re: Re: Mac vs. Amiga
Message-ID: <5283@ism780c.UUCP>
Date: Fri, 23-Jan-87 20:15:24 EST
Article-I.D.: ism780c.5283
Posted: Fri Jan 23 20:15:24 1987
Date-Received: Sat, 24-Jan-87 09:38:19 EST
References: <8520@topaz.RUTGERS.EDU> <1270@cbmvax.cbmvax.cbm.UUCP> <5240@ism780c.UUCP> <2312@jade.BERKELEY.EDU>
Reply-To: tim@ism780c.UUCP (Tim Smith)
Organization: Interactive Systems Corp., Santa Monica, CA
Lines: 32
Xref: mnetor comp.sys.amiga:1664 comp.sys.mac:946 comp.sys.m68k:155 comp.sys.misc:247

In article <2312@jade.BERKELEY.EDU> mwm@eris.BERKELEY.EDU (Mike Meyer) writes:
>>
>>Please explain how the Amiga has a real OS, but the Mac does 
>>not.  While you're at it, please explain why Amiga-DOS is a real 
>>OS, but PC/IX is not.
>
>My understanding is that this *IS* what the Mac provides. Once an
>applications program has control of the machine, it's got control of
>the machine, and has to wait for the program to give it back. There's
>no way for it to run code - either it's own, or another applications
>program - unless the application permits it. Am I wrong?
>

If I am running Switcher or Servant on a Mac, then I may have 
multiple programs loaded.  Context is switched by explicit action 
on my part, while, say, on my UNIX system, it can also be 
switched by explicit action on the part of the clock.  I don't 
see an essential difference as far as the operating-systemness of 
either system goes.  

Also, I thought that the Amiga only switched tasks when the currently
executing task does something that would block ( IO, or something like
the UNIX sleep or pause system calls )?  Is this so?

If someone can come up with a good definition of "operating system",
then it would be possible to decide which computers have them.  One
OS textbook I saw defined an operating system as the software that
takes control when a user program makes an error, but that definition
seems kind of worthless.
-- 
Tim Smith       USENET: sdcrdcf!ism780c!tim   Compuserve: 72257,3706
                Delphi or GEnie: mnementh