Using NULL as an illegal pointer

[Pete Delaney - Rockey Mountain UNIX Consultants]

Don't forget us word addressing folks, we have pointers that change length
as a function of environment(stack vs arg) and type (int vs char).  We use
two types of NULL pointers:

#define NULL		(char *)0	/* Default: worst case BASE + INDEX */
#define NULL_PTR	(int *)0	/* NOT Pointer to char */

All that kernel trapping code that assumes environment independence of pointers
is also fun to deal with.  Wish (Honeywell) Bull would switch to BYTE addressing.
					Pete Delaney