WIP: 16C firmware hack for more memory

[brouhaha]

Overflow handling wasn't terribly difficult. I've resolved all of the known bugs in the hacked 16C firmware. I'd be surprised if there weren't more bugs hiding in there. I wish I had a copy of HP's regression test suite.

HP's e^x routine is deliberately written to support a range up to 10^200. Beyond that it saturates at 10^200. While 10^100 is the overflow point for final user results, I think the 10^200 limit in the actual routine was to allow for extended range in intermediate results in other microcode functions that use e^x as a subroutine.