floats and doubles on a VAX 750 with an FPA

[Mats Wichmann]

All FP calcualtions in double? This hurts us even more on micros without 
FP hardware, and even WITH FP hardware. Yuck!!! We had to convert our
compiler to IEEE floating point, because that is what the hardware supported.
The penalty for float->double conversion is even bigger than for the DEC
format floating point.

The ANSI standard allows for, but unfortunately does *NOT* require, that floats
can be handled as floats instead of converting to double. 

As someone pointed out a while back this whole thing is historical, dating
back to a problem with the PDP-11 floating point instructions, and has been
allowed to continue ever since.