HP 71B HPIL questions and the HPCC!


Well, I just came back from London where I was fortunate enough to attend an HPCC meeting.

What a lot of information floating around that room! Wonderful way to spend 5 hours after being up for 24 hours, talk about overwhelming. Of course the conversation covered computer subjects such as Global Warming, Politics, Health systems and some HP computers.

Tony Duell spent many hours (yep! hours!) helping me understand wiring diagrams and logic testing on the HP 65 and other calculator chips. I can't believe his diagrams are all reverse engineered and drawn by hand. Who needs CAD when you have Tony's ability. Wlodek of course is a font of information and supplied me with an HP 41C top shell (keyboard and display) to replace my defunct delaminated HP 41C (my first 41 purchased in 81), and I am please to say the operation was successful ;-)

In any case, Tony introduced me to his Lab essentials which include, aside from his Desk Top items, an HP 41CX, about 50 rom modules from the mundane to the exotic, programmers and of course his card reader HP 71B.

I had never seen an HP 71B in person and the BASIC non RPN turned me off when it came out. Considering the amount of time I put into the 41CX writing programs, synthetics and running lab equipment with the HPIL back in the early 80's I wasn't about to change midstream.

Back to the point, what a sweet machine it is! So, I am now waiting for one in the mail. I have secured a card reader from a fellow MoHPC as well as a 32K rom module and an HPIL module and cords. I have an HP9114B fully operational and use it with my HP 41CX at the moment.

Now for the questions:

1.  I have an HP 9114B which I use as a back up for my various states of the HP41, will the HP71B work with the HPIL and the 9114B?

2a Can I use the HP 71B emulator to write programs, transfer to a disc and then insert the disc into the 9114B to copy the program into the 71B via the HPIL cable and 9114B?

2b. Will the above work in the opposite direction?

3. If not, is the only way to communicate with the PC via the HP-IL/RS-232 interface 82164A?

Of course, if anyone will be at the HPCC in May in London I might be there also, won't know until closer to the end of April, but after the information overload last time it WILL be beer call that Saturday evening!

Cheers, Geoff


  1. Yes, if you have the 82401A HP-IL adapter.
  2. Yes to both a and b. The disk format used by the 9114A isn't standard PC disk format, at either the physical or logical level, but there are programs to deal with that. On Linux, you can use Tony Duell's lifutils, though I'm surprised that I can't seem to find the URL for it at the moment. It used to be on the HPCC site at http://www.hpcc.org/hpil/lif_utils.html, but apparently is no longer there.

    For DOS, HP/Agilent published LIFUTIL; I'm not sure if it will work under Windows.


1. I have an HP 9114B which I use as a back up for my various states of the HP41, will the HP71B work with the HPIL and the 9114B?

Yes. And, it can use more of the disk. IIRC, the 41 can only use a fraction of a 720KB diskette. But, if you have the Ext-I/O module you can get around it.
2a Can I use the HP 71B emulator to write programs, transfer to a disc and then insert the disc into the 9114B to copy the program into the 71B via the HPIL cable and 9114B?

If you run EMU71 under DOS (or Windows 95/98, NOT NT/XP/2003/etc...) then you can write directly to the DOS A: drive. Then shuttle that over to the 9114B. NOTE: EMU71 cannot format diskettes, so you will need to do that in the 9114B or get LIFUTIL from Agilent. Linux users can use Tony Duell's lifutils. I think you can format a diskette with lifutils under Linux just by using lifdump to write out an empty image created by EMU71.
2b. Will the above work in the opposite direction?


3. If not, is the only way to communicate with the PC via the HP-IL/RS-232 interface 82164A?

No. Get an HP-IL ISA adapter with registered EMU71. I believe that Christoph Klug still has a few for sale. You'll need a PC with ISA slots. I recommend a junky used machine--put Windows 95 or Linux on it with some type of remote access and put it in the corner of your office, then run some long HP-IL cables to your desk, and remotely access your "HP-IL Appliance" with VNC, SSH, etc... with your shinny modern notebook (yes even your Mac). EMU71 and EMU41 with an HP-IL adapter is just like having a real 71B or 41CX attached to your 71B/41CX via HP-IL. It is the easiest way to transfer code, do backups, share virtual printers and displays, etc...


Looks like a little bit of work but at the moment I have a functioning HP9914B, spare 780K discs and just resurrected a windows 98 machine from the garage!

The EMU41C emulator is working in XP via a dos window and the EMU71B should be the same.

At the moment I have not required the need to learn basic but this will give me the opportunity to learn it. My background at university was punch cards and ALGOL W and then fortran. Other than HP and HPL that is the extent of my programming!

Well if I am bored at work or on layovers, I have some heavy reading to do!

Cheers, Geoff


Try to get the hard-to-find HP-41 Translator ROM module for your 71B. Then you can do BASIC, RPN (41CX-based), and FORTH all on the same machine. All your existing RPN 41CX code that does not require any special modules should work.

Oh, don't forget the all important Math ROM. That can be burned to 32K or greater EEPROM. A 64K EEPROM with Math and JPC is the way to go. Sadly you cannot burn the HP-41 Translator ROM.

Edited: 22 Apr 2008, 5:18 p.m.


My background at university was punch cards and ALGOL W and then fortran.

If you know fortran, you almost know BASIC. They are quite similar, especially in the constructs, but with variations in the exact syntax (and, depending on the exact BASIC, you may be stuck with one or two letter/number variable names).


now that I have the hardware and software for program transfers:

Lift disc utility for DOS,
Computer with floppy A: drive and 780K discs,
Windows 98,
EMU71B emulator,
HPIL module and cable to HP9114B,

Does anyone have a reference to Basic programming guide for the version that the HP71B uses. I.E. "prgramming in Basic for dummy's" circa 1985?



You can find the Basic Made Easy book by Joe Horn on the DVD from this site.




One thing I always liked about the HP manuals was that I could start at the beginning and just read through to the end, and finish with a feeling that I knew the computer without ever having gotten to "the hard part." That's what I did with the 71 Owner's Manual as well in the late 1980's. It really is well written.

I would not classify the HP-71's BASIC along with other BASICS though, as it was so much more powerful, especially when you have the IL module, math ROM, Forth/Assembler module, and a lot of LEX files in RAM from the user groups, as I have. After having a good command of the 71, I remember learning DOS and GWBASIC and feeling like I was taking an absolutely huge step down in capabilities. Then we got HP BASIC 5.1 (Rocky Mountain BASIC) in a 68000-based HP-9000-series computer at work for instrumentation, and although it had a few things my 71 did not, for the most part that felt very limiting too compared to the 71.


Besides HP Basic made easy by Joseph Horn, which was also translated in to Germany, and a French translation which is on
there is The Basic HP-71 by Richard Harvey,
and a German book VIEWEG : Praktische Anwendungen mit den HP-71B.



Hi, Geoff:

    Welcome to the ever-growing club of HP-71B admirers.

    I don't know about you but myself, I prefer lots of sample code over thick manuals or technical books when learning some new system, machine, or programming language. I find it much easier to learn by example, and much more productive; five lines of good, clear code can put me in track and make me understand how things get done, what can be done, and how practical tasks are implemented much faster than any dry "Reference Manual".

    So, although the HP-71B Owner's Manual is very well written and the books mentioned are also pretty good, and all of them are
    mandatory reading, you may want to complement them by having a look at the many articles I've written featuring the HP-71B, all of which do include short BASIC programs for it dealing with quite interesting matters, with plenty of routines and programming techniques being discussed along the way.

    You can freely download the articles in PDF format from this URL:

    My HP-71B related articles

    You can also download the math & programming challenges I've issued over the years, most of which do include HP-71B code to solve them, often quite optimized and using pretty tricky techniques. They can be freely download (also in PDF format, whole thread including all solutions and comments) from this URL:

    My math & programming challenges

    Finally, I'm including the abstracts of all downloadable HP-71B related articles present there, for you to get an idea of what's available:

    1. Long Live the HP-71B !

        This is a 12-page affair which includes two wonderful photographs, as well as a brand-new program I've written specifically for it, which in just 6 lines of code (!) manages to generate and print user-defined stereograms, viewable from the printed page or monitor output (Emu71 or HP-IL monitor) in full, glorious 3-D ! Three sample generated stereograms are included, one of them being a 3-D HP logo :-)

    2. Boldly Going - Identifying Constants

        This is a 14-page article which includes a truly awesome (if simple) program which allows ye goode olde HP-71B to perform some rather impressive 'symbolic' feats. The program does not require any additional ROMs or files, just a bare bones HP-71B, and can be converted to any other suitably fast HP model or emulator with minimum effort.

        It's a relatively simple program which provides basic functionality for an advanced, very useful and most impressive feature which is nevertheless absent in our beloved machines’ built-in instruction sets, namely identifying numeric constants, i.e., the capability of, given some real, numeric value, to try and identify its exact symbolic form if possible, and that failing, to provide an approximate symbolic expression of user-specified relative accuracy.

        This will allow us to perform some pretty nifty feats, such as give exact, symbolic
        results for definite integrals (even if they can’t be expressed in terms of elementary functions), finite or infinite summations, simplifications, and specific values of transcendental functions, among other uses.

        The full 14-page article boasts more than 40 worked out examples, including the five shown in this first page, as well as three detailed extensions, the last being an 'exercise' for the reader, solution included ! :-)

    3. Boldly Going - Matrix Square Root

        This 6-page article deals with the task of finding the matrix square root of square matrices. Two full programs are featured: a 7-line subprogram for the HP-71B which can deal with real- or complex-valued NxN matrices, and a 45-step routine for the HP-15C which will find the square root of real-valued matrices up to 4x4. Full examples are provided, with comments and notes, as well as the underlying algorithm.

    4. Small Fry - Primes A'counting

        This 1-page article deals with the topic of prime counting, i.e., finding out how many prime numbers there are up to a given limit N. For large N, generating all primes up to N and returning the count is prohibitively expensive in terms of running time and/or memory usage. What can we do about it when N goes sky-high (say 1010, 1015, or higher) ? The article features an 8-line user-defined function for the HP-71B to accomplish the feat very quickly, as well as several comparative examples against other well-known prime counting procedures.

    5. 25 Years of Othello

        8-page article to commemorate the 25th Anniversary of my HP-41C Othello program. If you liked the materials in RCL 20 you're bound to love this one, as it reminisces on those wonderful times when the HP-41C was brand-new and everything seemed possible.

        The article tells the whole story about how my 41C Othello program came to be, with its downs and its ups, and includes never-published-before letters from HP Corvallis, as well as a recreation of the original 41C Othello to run in an HP-71B or under Emu71, in the form of a 43-line, 2 Kb program with full instructions and examples so that you can test your wits playing this challenging 8x8 board game against it, to try and feel what 41C users felt when seeing it for the first time 25 years ago.

    6. HP-71B Short & Sweet Sudoku Solver / Sudoku Solver's Sublime Sequel / Sudoku Generator & Coach

        The whole Sudoku trilogy, these are a 10-page article, a 9-page article, and a 14-page one, which implement a compact but powerful recursive Sudoku solver algorithm, capable of solving any solvable puzzle fast, a puzzle generator, and a coach !. The first article describes a basic solver, with full details of its advanced implementation techniques, such as bitboards and boolean operators, while the second further enhances it with additional algorithms to speed up the search tremendously. A comprehensive, carefully crafted Test Suite is included, which can be used to test other solvers or even your own Sudoku abilities.

        Finally, the third article implements a Sudoku generator & coach, which can generate an essentially infinite number of puzzles per the user's specifications, including number of empty places, symmetries and, optionally, guaranteed uniqueness and solvability without guessing ever being necessary, in a fully ergonomic, printable format. The coach part can give appropriate hints of various types, one by one, guaranteed to be deductible by the user in the givenorder, either fully completing the puzzle or stopping midway, both for the self-generated puzzless or externally provided ones

    7. HP-71B Minimax Polynomial Fit

        12-page article. In case you're not too keen on curve fitting, a minimax polynomial is about the very best (and most difficult to compute!) way to fit a polynomial to any dataset or function. Minimax curve fitting isn't actually seen more frequently in literature and applications because of its inherently difficult implementation. But if you need to fit some data and a polynomial is adequate (after some data transformations if necessary), look no further. Four thoroughly detailed examples included.

    8. Mean Matrices

        11-page article, which introduces some new specially designed matrices I created myself, which are extremely troublesome to handle for the purposes of system solving, matrix inversion, or determinant computation. Unlike Hilbert matrices, which can't be represented exactly in finite floating point models, my matrices include only small, 2-digit integer values, yet are nearly intractable by anything short of exact, arbitrary-precision arithmetic. Examples are given and discussed in full detail, and exact Mathematica-produced results are also included for comparison purposes.

    9. HP-71B Fantastic FOUR

        8-page article, which discusses how you can use Fast Fourier Transforms (FFT) to multiply two very high-precision numbers faster than with any other algorithms currently known. Includes a very short, 10-line subprogram (can be formatted to just 8 lines) which will accept two numbers up to 1024 digits long and ouput their product (up to 2048 digits long). Running time is nearly linear in the size of the inputs compared to quadratic times for the usual 'school' algorithm (for instance, multiplying two 512-digit numbers using FFT is already 4 times faster on the HP-71B than with the usual method). Examples included.

    10. HP-71B Math ROM Baker's Dozen (Vols. 1 and 2)

        18-page article, in two parts, featuring 13 assorted mini-topics discussing novel aspects of using the extremely powerful and versatile Math plug-in ROM for the HP-71B.

    11. HP-71B Modest Mater

        12-page article, includes a relatively short BASIC program for the HP-71B that, given a typical 'Mate-in-N-moves' problem chess position, will recursively search for the solution. Full explanation of its inner workings is provided, as well as two complete, amazing examples.

Best regards from V.


Dear HP41 & HP71 handheld computer enthusiasts :-)

For handheld computer - PC transfer using EMU41 or EMU71 plus the HP-IL/PC Interface Card is the best solution - much better than using the HP9114B disk drive. On PC side an ISA slot is needed, most second hand low price PC hardware will work for this application.

For HP41 I create some program samples and a user manual for HP41-PC data and program transfer - following this documentation you get a working system in short time - without reading voluminously books.

Yes - less samples of the HP-IL/PC Interface Card are availabel from me :-)

Best regards - Christoph Klug

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