Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!nuchat!sugar!peter
From: peter@sugar.hackercorp.com (Peter da Silva)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Address Spaces (was Re: (Fairly) Complete Amiga VM design)
Keywords: virtual memory, address space
Message-ID: <3928@sugar.hackercorp.com>
Date: 14 Jun 89 23:46:37 GMT
References: <8906010252.AA11810@jade.berkeley.edu> <367@xdos.UUCP> <55595@linus.UUCP>
Organization: Sugar Land Unix - Houston
Lines: 26

In article <55595@linus.UUCP>, eachus@mbunix.mitre.org (Robert Eachus) writes:
>      On almost all "separate address space" time-sharing systems, part
> of the address space (managed by the OS) is mapped into all user
> adress spaces.  VM for IBM mainframes is probably the only major
> exception.

A significant exception, at least for this forum, is UNIX.

> permitted code to be loaded without relocation.  The VAX and 68000
> were both desinged to support this since it made linking and loading
> much easier.

(Raised eyebrow) Don't you mean harder?

You can't write generally position independant code on the 68000. You
can't write to a PC-relative location, so you have to burn an address
register.

>      The Amiga from day one has required that code be written this
> way, and on the 68000 family this type of code is generally faster.

No, the Amiga doesn't require this. When LoadSeg runs it actually patches
all the code to the specific load address. This makes swapping, um, painful.
-- 
Peter "Have you hugged your wolf today" da Silva      `-_-'
...texbell!sugar!peter, or peter@sugar.hackercorp.com  'U`