HP 35 ROM fault?

[teenix]

(11-21-2016 10:52 PM)Harald Wrote:  I have replaced the faulty anode driver and now have a mostly working early HP 35 with split battery compartment and 2.02 bug.
Mostly working because sin, cos, arc sin and arc cos don't work. Everything else, even tan, works. Excecuting the non working functions results in a blank display and a crashed calculator, so I suspect a bad ROM. Would anybody know which instructions are only use by those four functions and which of the three ROMs that would reside in?

Cheers,
Harald

Looking at the 35 microcode execute in my emulator, the code for these functions appears to be split over ROM 1 and 2.

cheers

Tony