NavList:

Hi Rafael,

I thought I'd chime in on the early HP calculators---I too am a fan.

As you say, the HP-35 would have been the first viable handheld calculator for celestial navigation.  I wonder if four-function calculators could have been pressed into service somehow---maybe with a table of Taylor series or other polynomial or rational approximants---but it's debatable whether that's really better than pure paper tables.  Once you have a scientific calculator, though, it's clearly game over.

I have an interest in reverse-engineering early VLSI chips to recover gate-accurate models.  The HP calculator chips are a natural target:  simple process (metal-gate PMOS), low transistor count, large features (~8 micron).  I imaged several of the HP-45 chips some time back---the 10-register RAM chip, for example, can be seen here:

I'd like to image and polygonize the full set of HP-35 chips.  It would be a fitting task for year 50 of the design.  Once the gate-level netlist is captured in HDL, it can be resynthesized onto any modern platform while retaining transistor- and cycle-level accuracy.

Cheers,

Peter