2.16: What is deadbeef?

When running the debugger (dbx), you may have wondered what the
'deadbeef' is you occasionally see in registers.  Do note, that
0xdeadbeef is a hexadecimal number that also happens to be some kind
of word (the RS/6000 was built in Texas!), and this hexadecimal number
is simply put into unused registers at some time, probably during
program startup.