HP-34C Questions


After seeing several threads about the 34C, I started reading my copy of the Owner's Handbook from the HP Museum's DVD. I had always wanted a 34C but it was just too expensive back then. I also lusted after an HP-97 but that way way out of my league (last year I finally got one).

Anyway, on page 7 of the handbook, it says that there are 72 data storage registers. That doesn't make any sense as there are only 21 data storage registers of which 20 can be added to the basic 70 programming steps for a total of 210 programming steps. I assume this is a typo but please confirm in case I missed something.

My first calculators were the HP-45 and HP-55 and so I'm very familiar with how those classic handbooks were laid out. On page 15 of the HP-34 Handbook, it mentions another book called "Solving Problems With Your Hewlett-Packard Calculator." I found a copy of it on the DVD under the HP-31E. After scanning through it, it appears that the older, classic series handbooks were split for the 30-series into a generic HP RPN usage book and calculator specific handbook. Was the Solving Problems handbook shipped with all 30-series calculators as I'm guessing?

I'm interested in taking the examples in the 34C handbook and trying them out on my 97. They appear to be very similar in terms of capability except for the continuous memory, numerical integration and printing. It's fun for me to play around with this. Everyone here at work now knows of my interest in calculators after I went to HHC 2008 conference, everyone likes to joke about my geeky interest. But it's okay, everyone has a quirky side to them.



I'm not sure exactly how they derive a count of 72, but the 34C does have a fair number of internal storage registers dedicated to the solve and integrate functions.

On the 15C, instead of dedicated registers, these come from the "pool", so that when you're not using them for solve and/or integrate, you can use them for general data registers or program steps.


HP-34C was my first HP calculator and my first programmable device (I decided to work in IT because of it). I know it very well.

The calc has 20 registers, the I register for indirect addressing and 70 programming steps. The calc can convert automatically the 20 registers to reach 210 programming steps (20 * 7 + 70 = 210).


Anyway, on page 7 of the handbook, it says that there are 72 data storage registers.

Gerry --

The version on the MoHPC CD-ROM is Revision C, August 1980. I have paper copies of this version and of Revision B, April 1980. Neither of them claim "72 data storage registers".

  • There are the 20 allocatable registers, the I-register, the stack, and LASTx for 26 user-accessible data-storage registers.

  • There are also 10 non-allocatable registers for programming (* 7 bytes/register * 1 instruction/byte = 70 instructions).

  • 23 non-allocatable registers are reserved for SOLVE and INTEG.

    The first two bullets are illustrated on page 7. Nothing on page 21 or page 55 contradicts what is stated earlier in the manual.

    -- KS

    Edited: 23 Nov 2008, 12:53 a.m.

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