more on Opinions Re: Apple to ditch IBM, switch to Intel chips rumor on CNet

[David Farber <dave () farber net>]

Begin forwarded message:

From: John Levine <johnl () iecc com>
Date: June 4, 2005 4:51:28 PM EDT
To: Roman Gollent <roman-ip () gollent com>
Cc: dave () farber net
Subject: Re: more on Opinions Re: [IP] Apple to ditch IBM, switch to  
Intel chips rumor on CNet


> Two words: Fat Binaries

Two more words: byte order

M68K and PPC use the same data formats, same byte order, same
everything else in data files and internal data structures.  But x86
uses the opposite byte order from M68K and PPC.

Recompiling programs is (to oversimplify somewhat) a one-time painful
exercise for developers, but sharing files between machines with
different data formats is an unending source of pain.  In theory you
can audit the code and find all the places where you read and write
data structures and do the reordering where you need to and eventually
try to move everything to XML stream formats where byte order isn't an
issue.  In practice, you'll spend your life picking bugs from places
in your code where you hadn't noticed the byte order dependencies, and
each time the failure will be either that something looks wierd in a
document, or an application crashes when you feed it one file even
though it was OK on the hundred previous file.

It's certainly true that the economies of scale in wintel hardware
are compelling, but the costs of switching are way higher than it was
for M68K->PPC.  I'll be interested to see what's really going to happen.

R's,
John



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