HP-35, HP-65 .... reverse engineering latest news


What's new on my site ?

- I started the HP-65's ROM exploration. A Java simulator is already running the HP-65 micro-code without problem, allowing to study how the program storage circuit is working ; its program memory symbolic addressing and its hardware label-searching mechanism are very original. http://www.jacques-laporte.org/sim65.htm

- The reverse engineering of the power units for the Classic (HP-35; HP-45) and Woodstock series (HP21, HP25) is published.
This job has been completed with the precious help of Daniel WEED - ex-rocket scientist from Phoenix, AZ. Dan did a nice job deconstructing the power unit of the HP-45 and repairing one unit with modern discrete composants.

- January 2007, I started to publish the HP-35 hardware pages. It is a kind of "black box" reverse engineering: you can't open a chip to see what's going on inside. But I had input and output signal traces on my scope and in mind the 1972 state of the art (sometimes though it is hard to follow, because of HP ingenuity for example the way they mixed PMOS chips and TTL logic, or the efficient inductive drive technique used for the LED display is great art!

- The HP 35 ROM Mapping is finally on line (a very hard work) : "The HP-35 firmware decoded & other mysteries".

Enjoy and please give feedback.

Edited: 20 July 2007, 5:10 a.m. after one or more responses were posted


Some of you guys are just TOO smart! :^)

I can't figure out half of what people are saying around here.

Oh, well.


Bonsoir Jacques,

I must admit I didn't know your site until today, and was discovering a real new world this evening. Your site appears very properly designed, and there is a lot of knowledge stored therein, which will cost me many nights to read (not knowing if I will at any time reach the level to understand a considerable fraction of the material you published). Merci bien!


Hi Jacques!

I'll be glad to help with the HP-65 write-up and photos. I have done repair work on these, the 67 and 97. Great web site there with lots of info. A lot of folks might like the Cordic explanations too!

-- Dan W.

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