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Tear Down: Scientific calculator boils design down to two ICs

Note that the second chip is an SRAM, not a flash memory.

The really interesting paragraph from this article is:

Unlike one of the predecessor models (the 41), there's no way for the user to tap in to the 35s' firmware. The programming only occurs at the user level, although HP is tinkering with giving users limited access to the firmware

Wow, that would be awfully nice and I'd start using my 35s again. I wonder if there is some hidden command or whether this would entail a new version of the machine.


Katie, too bad you weren't at HHC2007!

[that was a tease -- sorry!]

Edited: 1 Feb 2008, 11:11 p.m.

I suspected I'd get a response like yours :)

So you're going to leave me to guess if:

A) A new 35s is on the horizon.


B) The existing 35s does have a hook into the firmware that was told to the HHC 2007 participants and they haven't yet leaked it. Kim's term "tinkering" could be construed to imply exactly this.

I'm going to guess it's (B) and I'm going to further guess that the access to the firmware is via EQN based on the undocumented STO command that works in EQN. But that's as far as I can go without another hint. Any takers..... :)


Those of us that were there and signed the NDA are not prohibited from discussing things that we were NOT told. As far as I can recall, we were not told anything about back doors in the 35s firmware. I very much doubt that there are any.

Was there NO talk about a trade in program for the buggy old 35s? ;^)

Do you mean buggy thirtyfives, or buggy thirtyfive-esses?

For the former, there was a trade in program, but it's long since over.

If there's a bug in the 35s that's actually interfering with your use of the calculator, I'd contact HP about it. I have no idea what, if anything, they'll do for you if you contact them, but I do know what they'll do for you if you don't contact them.

I was thinking about what HP already did about 35 and 32SII customers. At that time, there were programs to change calculators IIRC. It would be a nice gesture at least to let customers have access to an updated 35s for a small amout to compensate for shipping / production costs, something like this. I'm probably asking to much...

There's one thing about this 35s I'm still asking myself : Why the hell did our HP fellows made it programmable, since the very first one from 35 years ago was not programmable at all and only had the very basic trig function ? Are Bill and Dave suddenly resurrected ??? What a joy !!!!