Path: utzoo!attcan!uunet!samsung!gem.mps.ohio-state.edu!apple!apple.com!chewy
From: chewy@apple.com (Paul Snively)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Tail patches
Message-ID: <5320@internal.Apple.COM>
Date: 21 Nov 89 01:37:31 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 43
References:<5249@internal.Apple.COM> <17090@dartvax.Dartmouth.EDU> <5292@internal.Apple.COM> <1989Nov20.182741.2658@eng.umd.edu>

In article <1989Nov20.182741.2658@eng.umd.edu> russotto@eng.umd.edu 
(Matthew T. Russotto) writes:
> In article <5292@internal.Apple.COM> chewy@apple.com (Paul Snively) 
writes:
> >In article <17090@dartvax.Dartmouth.EDU> erics@eleazar.dartmouth.edu 
(Eric 
> >Schlegel) writes:
> >> On pp. 385-6 of IM, volume 2, is documented the Restart procedure. 
It's 
> >> marked Not in ROM; assembly-language programmers are advised that 
"you 
> >can
> >> give the following instructions to restart the system:"
> >>      MOVE   ROMBase,A0
> >>      JMP    $0A(A0)
> >
> >This raises an interesting point: Inside Macintosh actually does 
> >programmers a disservice by saying things like "assembly-language 
> >programmers can..." and then giving code that relies on specific ROM 
> >addresses (or even specific ROM offsets, like above).  The CORRECT way 
to 
> >get that same effect, given that there's a routine called RESTART that 
is 
> >marked NOT IN ROM is to Link in the appropriate library (usually 
Runtime.o 
> >for MPW users) from your development system, and make the call to the 
> >library routine.  That's what libraries are for.
> So?  Your application still breaks.  Unless you have a dynamic linker,
> of course... (was it REALLY that hard for apple to keep a JMP to the 
right
> spot in 0A(RomBase)? )

Your application won't break as long as you link with up-to-date library 
code!  As for "was it hard to keep the jump," I'm not a ROM engineer, so I 
don't really know.  There were some pretty hairy changes in going from the 
old Macs to the II-family Macs.

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Just because I work for Apple Computer, Inc. doesn't mean that they 
believe what I believe or vice-versa.
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C++ -- The language in which only friends can access your private members.
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