Subject: [netatalk-admins] FAT and 68k

From: "Yannai A. Gonczarowski" <[email-masked]>
Date: Sat, 19 Jul 1997 11:46:35 +0300

Can anyone tell me what's the difference between a 68k binary and a FAT
binary, and if my MAC runs them both, which should I use? (I have
noticed that 68k binaries often take less disk space, but leave that
aside, are there any performance differences?)

Thanks,
Bye,
Yannai.

--
Yannai A. Gonczarowski     System Administrator    
[email-masked]
The Hebrew University High School     
http://www.leyada.jlm.k12.il/~yannaigo/

"Do you want to know something? Everybody's human."
"I find that remark insulting."
  - Kirk and Spock, "Star Trek VI: The Undiscovered contry", stardate
9529.1

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From: Peter Gutowski <[email-masked]>
Date: Sat, 19 Jul 1997 05:38:42 -0400 (EDT)

Fat binaries contain 68k code resources in the resource forks *and* power
pc native code in its data fork. On a 68k machine, the "normal" 68k code
would be executed and on  power pc hardware, the sytem would first look
for executable application code in the data fork (there is also a resource
present the also flags the existence of this power pc code). If a power pc
machine does not find native ppc code, it uses the its 68k emulation to
run the 68k code, theoretically with some performance penalty. 68k
binaries do not have any ppc code in the data fork. 

A powerpc system runs fastest when executing native ppc code.
Unfortunately, so much of the low level OS is still 68k code (and will
remain so even with the upcoming 8.0 release) so that the potential power
of the ppc's risc processor is still pretty much untapped. This is even
more distressing since Apple et al have been selling ppc machines now for
4 or 5 yesrs! And finally, because simply changing between executing ppc
code and 68k code involves some change-over time, performance is further
robbed. The net result is that PPCs *are* faster, but have the potential
of
being *very much* faster than they can run right now.

Peter Gutowski
email: [email-masked]
http://www.powervue.com/~peterg