curiousmarc

Lots of HP Nanoprocessors and TI Clock Chips

Added 2020-10-04 02:52:38 +0000 UTC

My previous video on TI clock chips was a (rewarding) detour on the road to repair my HP 98035 clock modules. Thanks to the contributions of former HP 9825 developer Steve Leibson http://www.hp9825.com/ Patron Jack Rubin, collector Bob Rosenbloom https://youtu.be/2OkTm0vI7As and vintage HP warehouse extraordinaire Ed Blacksmith https://youtu.be/qn2Zz8X41dI I have now acquired no less than 6 HP 98035 clock modules. And zero of them work. Zilch, nada, nothing. Even after changing the batteries and a few clock chips.

Well, not anymore! Thanks to my TI chip breadboard LED watch and the recent Nanoprocessor reverse engineering by Ken Shirriff with the help of Antoine Bercovicci http://www.righto.com/2020/09/hp-nanoprocessor-part-ii-reverse.html I have now gained a much better understanding of the two boards in this module. Enough to repair 6 cards to make 3 modules (see story in the pictures and legends).

Damage so far: 4 bad clock chips, two bad CD4069UB hex inverters, one bad 1 MHz crystal, one bad 32.768 kHz crystal, a connector with a hidden broken pin and a bad PCB. My most hacked repair was the board with internal wires eaten by the battery leakage, which necessitated a whole bunch of bodge wires to finally bring it back to life.

And I even found what our mysterious 3rd button does on the watch chip, by looking at the disassembled Nanoprocessor ROM code: it's a clock hold button, only works in conjunction with pressing and holding the read button to display the seconds. It will stop the seconds from advancing.

3 working modules is more than I need, but should I unleash the big test HP weaponry and coerce the rest of the boards into submission through logic analysis? What do you think?