Rumors are flying that Apple will announce a switch to Intel processors on Monday. This wouldn't surprise me much. I think Apple hates being dependent on IBM for processor advances, which are critical for them to be competitive. Apple has successfully made it through a couple of other large jumps like this - first from 68k processors to the PowerPC, and from Mac OS 9 to Mac OS X.
The timing seems pretty good. When there were rumors about this a couple of years ago, it was just after developers had spent a bunch of time and money upgrading their applications to run on MacOS X by carbonizing them or rewriting them. It would be really tough on developers to ask them to turn around and do the Intel work (meaning they have no time for feature work). Customers don't really appreciate the huge amount of work that can go into changes like this and don't like to spend money on an upgrade that just makes an application run like it used to, but on an updated platform.
One of the technical hurdles for many applications will be the the difference in endian-ness between the two processors. Say you have a 2-byte variable with the number 1 stored in it. On a PowerPC processor, the first byte in memory will be 0 and the second byte will be 1. On an Intel processor, this is flipped around. So, if an application writes binary data to a file, the developers will need to do work to swap bytes around as it reads/writes. As another example, Unicode strings are made up of two-byte characters and are typically put onto the clipboard with big endian (PowerPC) byte layout. Applications will have to figure out the byte order and swap if necessary. Luckily, Unicode has a standard mechanism to help with this problem - a byte order mark at the beginning of the string. There are a few factors that will help out with the file format issue:
- XML has been taking off as a popular file format, which doesn't have endian issues, except in any embedded binary data.
- Many of the big applications are cross platform already and have probably dealt with the endian issues to some degree.
- Cocoa apps can rely on Cocoa to serialize data, and Apple can do the endian work so developers don't have to worry about it at all.
There's also the obvious problem that code written in PPC assembly won't work. However, I don't think there's a whole lot of that around any more. Virtual PC is one of the biggest exceptions I can think of, but that's a whole 'nother story :-)
When Apple switched to the PowerPC chips, Apple failed to provide good tools to developers, and Metrowerks appeared to save the day with an awesome new Mac development environment with great PowerPC support. Over the last few years, Apple has been putting more and more effort into powerful free development tools for the Mac, driving people away from Metrowerks. I wonder if this change will be the nail in Metrowerks coffin... That would be too bad.
Isn't it interesting times when the X-box is moving to PowerPC and Apple is moving to Intel?
