You are asking why does null pointer (or something near null pointer such as memory address 1), causes a segmentation fault. It is that way because null pointer has caused segmentation fault since the begin of computers in the 20th century, decades ago ( see http://en.wikipedia.org/wiki/Segmentation_fault and http://en.wikipedia.org/wiki/Null_pointer#Null_pointer). You may be also asking, why does an example that is intended to crash the perl interp crash the perl interp. The answer to that is, because it is an example to crash the perl interp. A different question is, why does the perl interp crash from that example, read my second sentence.