DUMP DU< DUP
DUMP ( addr len -- )  
ansi 15.6.1.1280 <TOOLS>
show a hex-dump of the given area, if it's more than a screenful it will ask using ?CR

You can easily cause a segmentation fault of something like that by accessing memory that does not belong to the pfe-process.

reference: p4_dump in ../src/toolkit.c:0159, export CO DUMP