>    Single source-code  for multiple CPU architectures is unlikely to be
>    worthwhile for any but the simplest applications, due to differences
>    in peripherals.

Thanks - you're helping me think.  This is "obvious", but I wasn't thinking
along the right direction.  I guess what I'm really looking for is any
techniques that people have found useful for "abstracting" microcontroller
peripherals so that the main body of code can be made more readable while
hiding the details in mcu-dependent definition files.  As an obvious but
useful example, we make extensive use of a value defined as "ONESEC" which
is the number of 'ticks' (incremented by a timer interrupt) that occur in
one second.  On most platforms, this was a constant, and usually 1000 (the
"clock" was kept in milliseconds), but I think I recall one platform where
the clock was an RC circuit of dubious accuracy and ONESEC was redefined to
a variable that was MEASURED (by crystal controlled CPU) at startup time.

BillW

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