Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!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: <5292@internal.Apple.COM>
Date: 20 Nov 89 17:34:36 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 45
References:<5249@internal.Apple.COM> <17090@dartvax.Dartmouth.EDU>

In article <17090@dartvax.Dartmouth.EDU> erics@eleazar.dartmouth.edu (Eric 
Schlegel) writes:
> Resource Header Application Bytes were 128 bytes of data at the beginning
> of a resource file that supposedly were available for application use.
> This is documented on pp. 128-9 of IM, volume 1. Tech Note 62, from Jan. 
1986,
> states that applications should no longer use these bytes as they're 
> reserved for future use by the Resource Manager.

Great, but did this actually break anything?

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.

In article <17090@dartvax.Dartmouth.EDU> erics@eleazar.dartmouth.edu (Eric 
Schlegel) writes:
> Sorry, Paul. The examples are few, far between, and obscure, but they
> do exist.

Indeed they do, but a) how much stuff breaks as a result of our System 
Software and hardware architectures evolving, and b) is it the software 
that's broken, the documentation, the hardware, or is it all a matter of 
interpretation?

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