🚀 go-pugleaf

Path: castor.usc.edu!blarson
From: blarson@castor.usc.edu (Bob Larson)
Newsgroups: mod.computers.68k
Subject: Re: Minix to the 68k?
Message-ID: <644@castor.usc.edu>
Date: 8 Feb 87 08:11:15 GMT
References: <8702070057.AA17890@amdcad.AMD.COM>
Reply-To: blarson@castor.usc.edu.UUCP (Bob Larson)
Organization: USC AIS, Los Angeles
Lines: 23

In article <8702070057.AA17890@amdcad.AMD.COM> bandy@amdcad.UUCP (Andy Beals) writes:
>Given that I'm a little shy on information about #3, I'd like to ask the
>Amiga gurus here how the Amiga manages to do multitasking. (for that matter,
>how does OS9 mangage it?)

All Os9 code (except for some system dependent stuff like the boot
code) is position indepentent and sharable.  When a program is
started, if it is not already in memory, (due to special request or
another user using it) it is loaded into avalable memory.  Data areas
are allocated seperatly.  Once memory has been allocated, it is not
released until it is no longer in use.  (Relocation does not occur
durring execution.) This allows return addresses, etc. to be pushed on
the stack in the normal manner.  Yes, this scheme does have the
clasical "fragmentation" problem, and does limit your processes to
physical memory, but a few extra kilobytes of memory is probably
cheaper than a MMU.  (This refers only to level I os9.  Level II, such
as will soon be released for the coco 3, does use an MMU.)

-- 
Bob Larson
Arpa: Blarson@Usc-Eclb.Arpa
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