fptrap \*- floating point interpreter
11/45 FP11-B floating point unit.
It works by intercepting illegal instruction
and decoding and executing the floating point operation codes.
In systems with real floating point,
there is a fake routine in /lib/liba.a with this name;
when simulation is desired,
the real version should be put in liba.a
A break point trap is given when a real
illegal instruction trap occurs.
Rounding mode is not interpreted.