CRAMPED is #define'd in inet.h as 0 for an 80836 processor or better and 1 for anything less (e.g., 8086). In the figures and discussions in this documentation, it is assumed that the system is an 80836 or better.
If the system is not even an 80386, it is a fair assumption that there is not much memory to work with (i.e., the memory is "cramped").