Hello, I was browsing through older posts that deal with the painful issue of portability (http://www.keil.com/forum/docs/thread8109.asp). I was (and still am) a big advocate of programming as much as possible conforming to the C standard, and having a layered structure that allowed "plugging-in" other hardware. But I have come to change my mind recently. I am reading the "ARM system developer's guide" (excellent book by the way. I'm reading it because I want to port some C167 code to an ARM9 environment) in which chapter 5 discusses writing efficient C code for an ARM. The point is, and it is fairly demonstrated, that even common, innocent looking C code can either be efficient of very inefficient on an ARM depending on specific choices made, let alone another processor used! So, if we are talking about squeezing every clock cycle out of a microcontroller - I do not believe that portability without ultimately littering the code is possible!
Per, You wrote: Anyone think they selected the correct processor if they didn't read the documentation before selecting it?
these thing do occur, alas, as we all know. A couple of overseas managers are now considering switching to Linux because it seems to support some powerful processors that Windows CE does not support (yet). The problem is the performance of a system that sports a powerful MX processor. They don't even consider revising the software, which needs a) rewritng by people who know what they are doing b) careful, controlled maintenance
but instead they plan to replace the RTOS and change the prcorssor, without fully understanding the costs in terms of compatibility and maintenance. Again - shocking.