The Museum of HP Calculators

HP Forum Archive 11

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In praise of the HP-34C
Message #1 Posted by Ex-PPC member on 28 Feb 2003, 6:53 a.m.

Norm Hill posted:

"Hi guys, Well guess I'm the only guy in town who thinks the 34C was the coolest unit."

For what it's worth, I also think the HP-34C is a great machine, and I'm not the only one to think so, several of my HP-fan friends do agree as well.

I was absolutely delighted to get one when it was released, and I liked very much its advanced features, Solve and Integrate, which were so incredibly well described in that legendary HP Journal issue from 1980 (IIRC) by their "father", Mr. Kahan. The fact that Solve could use Integrate and vice versa seemed to me incredibly powerful as well. The Owner's Handbook was also extremely well written, as went far above and beyond the call of duty to help the user make the most from this wonderful machine.

It also had a lot of good 'physical' points. For once, it seemed solid, the keys had a very nice, positive action, and the LED display was marveously clear, and of course, you could do what you couldn't with any of the later models: to use it in complete darkness !! I was very young at the time of its release, and I was enthralled to use it at night, while in bed, without turning the lights on and without disturbing anyone. The LEDs were bright enough to easily see the keyboard legends in full darkness. Try that with a 32S, 41C, 71B, ... !

Another good point is that it had a lot of memory for the time, and combined with the advanced programming capabilities, you could write quite complex programs, which wouldn't fit in a basic 41C, specially if they also made use of Solve/Integrate. Matter of fact, many of those programs wouldn't fit in a 32S/SII as well, because the Solve/Integrate functions in these models take a lot of the already small memory, leaving very, very little for your program/variables, also using more RAM per step (from 1.5 bytes upwards).

So the HP-34C was much admired, and sold very well. I still have a large number of advanced mathematical programs for it, and still remember how much I enjoyed writing them and seeing how easy it was and how well they fit in such a tiny but powerful calculator.

Finally, the HP-34C had its "synthetics" too !! There were a number of very interesting articles published in the state-of-the-art Australian PPC Technical Notes, dealing with ways to access different parts of the RAM, the Solve/Integrate registers, the decoding of the full intruction set hex table, etc, etc. It was awesome what people could and would do with this small marvel.

Definitely, you're not alone in your praise of it. Long live the HP-34C !

Re: In praise of the HP-34C
Message #2 Posted by Steve on 28 Feb 2003, 12:04 p.m.,
in response to message #1 by Ex-PPC member

Is it possible to still get the Aussy PPC Notes? Are they on the MoHPC DVD or Jake's DVD? Thanks!

What's a "Jake's DVD?"
Message #3 Posted by Spice_Man on 28 Feb 2003, 1:47 p.m.,
in response to message #2 by Steve

What is a "Jake's DVD?" What is on it? Much obliged!


Jake Schwartz has a set of CDs with great stuff on them!
Message #4 Posted by Gene on 28 Feb 2003, 3:43 p.m.,
in response to message #3 by Spice_Man

Well worth having!

Re: In praise of the HP-34C
Message #5 Posted by Luis on 28 Feb 2003, 1:51 p.m.,
in response to message #1 by Ex-PPC member

I agree 110% with you, as a 34C fan too but, I'm not sure there is chances in accessing the RAM in this machine. Could you tell us more how you can do it or even put some article available in this forum?

Cheers and Thanks!


Re: In praise of the HP-34C
Message #6 Posted by Ex-PPC member on 1 Mar 2003, 7:52 p.m.,
in response to message #5 by Luis

Luiz wrote:

"Could you tell us more how you can do it or even put some article available in this forum?"

Unless someone makes available scanned PDFs of the Australian PPC Technical Notes issues, I think the exact articles and details will be unlikely to be seen again. Seems that PPC TN issues are either completely lost or have never been scanned, as far as I know.

Regrettably, it's been long since I read those articles about accessing internal registers in the HP-34C, and I don't remember the specifics, but I feel it had something to do with interrupting the self-test at specific points, probably by turning off the machine while the test was in progress.

That would leave the program pointer at some internal registers, and then you would simply turn it on again, switch to program, and you would find instructions there, corresponding to the information stored in said internal registers. I have the vaguest idea that this could be used to create non-normalized displays, long-time decrementing counters and things like that, but not sure at all, sorry.

Re: In praise of the HP-34C
Message #7 Posted by Pyerre on 28 Feb 2003, 2:54 p.m.,
in response to message #1 by Ex-PPC member


Got one too...mib & perfect working order. A little bit behinh the lovely HP25, this HP34C still one of my favorites.


Re: In praise of the HP-34C
Message #8 Posted by Fred Lusk (CA) on 28 Feb 2003, 9:43 p.m.,
in response to message #1 by Ex-PPC member

I agree that the 34C is marvelous. I bought one my senior year of college about the first week it came out. The SOLVE function alone was worth the price of admission.

My best "trick" with the 34C was during my civil engineering hydraulics final. One of the problems required a lengthy iteration. Rather than work out the problem like everyone else HAD to, I wrote a program on the fly that included a SOLVE routine. My written solution consisted of writing down the equations, the data, the program listing with simple annotations and instructions, two guesses, and the result. I figured this method would be acceptable because my professor used an HP-45. I finished the two hour final in about an hour; the next fastest was about 1:45. I ended up with the highest score on the test, and (after a slow start) the highest grade in the class.


HP-34C Thanks Guys !
Message #9 Posted by Norm Hill on 1 Mar 2003, 2:36 a.m.,
in response to message #8 by Fred Lusk (CA)

Thanks Guys, for sticking up for the HP-34C. A museum picture-link down lower, you won't be disappointed ......

I thought I was gonna be the only one who saw the underlying beauty of the HP-34C.

It bridges the gap between really early units like HP-25C (those had some serious battery charging problems and inferior cosmetic appearances) but the HP-34C comes before the LCD units, which I don't enjoy viewing like the red-super-blaster LED displays. So its an in-between units with good capabilities but dynamite styling and bright-red led digits.

It has no "soft-keys" nor "menu" keys, each key is what-you-see-is-what-you-get YES!

NO, it's not the most powerful unit. But you can have one automobile design at 90 horsepower that is a real sweetheart of a car, durable, valuable, yet have another at 300 horsepower that costs too much, doesn't look right and doesn't handle right. You have to look at the whole package to see whether something was put together right or not. SO! LOOK AT THE WHOLE PACKAGE AT THIS LINK:

I DARE YOU, pull up that picture and give it a stare for a minute, and you are halfway to seeing the very face of God :o) That is so nicely prepared, by clever and dedicated people. Just look at the coloring of the keys, imagine those bright red digits, See how nicely it is sculpted and styled. YES it is a real sweetheart and I meant what I said, they should make them NEW just the same, to this day. WHAT WE GOT NOW? (hp-32s) BROWN ??????? LCD ??????? ORANGE 2nd functions on BROWN ????? What is it, designed on Halloween? Is it a pumpkin in a patch ?

The HP-32S (or HP-41C) is more powerful than 34C yes, prettier no. Which is more fun to learn & use for easier problems? I'd take the HP-34C !

Re: HP-34C Thanks Guys !
Message #10 Posted by Patrick on 3 Mar 2003, 10:32 p.m.,
in response to message #9 by Norm Hill

Hate to spoil a great party, but...

I was always a Woodstock fan. I had a wonderful HP-25 for years and thought its form factor to be next to perfection.

When the HP-30 series came out my first impression was that HP had cut back on quality in order to reduce the price. It just didn't feel as solid or well made sitting in my hand. It will come as no surprise to you that I never did buy a calculator from that series. I went from 25 to 41.

Has history proven me wrong? Has this series held up quality-wise to the same degree as the Woodstock or Voyager series?

Reliability HP-25 vs HP-34C
Message #11 Posted by Norm Hill on 4 Mar 2003, 12:00 a.m.,
in response to message #10 by Patrick

If you check the page for HP-34C, you will see that there was an early version of the circuit board that used pressure to hold connections together and that the earlier HP-34C was unreliable.

After they fixed that, I don't know exactly how reliable they are. Probably OK. The HP-25 has got a serious problem that the charger module puts out high voltage, and its the battery that's clamping down the voltage and limiting it. If you pull the battery pack with the charger plugged into the calculator the voltage shoots up and you are very close to blowing all the IC's, or maybe you actually will.

Pretty darn amateur, but it was a new era and they figured you wouldn't do that. Don't know if the HP-34C has the same weakness. Better not pull your battery pack with the charger on.

A clever fellow could add a couple of 3.3V zener diodes in series and create some protection against overvoltage (clamp it around 7V).

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