if(p)

[Peter da Silva]

Question: isn't this all rather moot? I mean, what sort of architecture could
you actually run 'C' on that doesn't allow the use of zero as a null pointer?
If nothing else you can always add a shim at 0000:0000 (or whatever weird
method you use for indicating segments). I mean: there's nothing in the PDP-11
architecture that says that 0 is a natural value for NULL. In fact 1 or FFFF
would probably make more sense (seeing as they're odd addresses).