TY. I am ignorant of the compiler side of the process here. My mental model as a former numerical algorithms guy at the time was that the x87 chips performed the 80 bit operations as opaque internal operations, and returned the visible results back as 32/64 bit IEEE754 floating point format bytes.

Is that inaccurate? If not how did you store the extra 16 bits (DP)? I should've bought a zortech compiler back in the day? ;-)

I am sorry that Borland hooked me with turbo-p and then jacked me up with turbo-c/c++.