I didn't program these things, but the PPC stuff is available at: http://www.pahhc.org/ppccdrom.htm (for a price). BTW, Paul, you're undoubtedly aware that an explicit conditional branch isn't required for a computer to be Turing complete . E.g., a purely declarative language like Prolog (where "branching" is accomplished by the underlying theorem prover, not in the programmer's code) can be Turing equivalent. Were there users' group for the old programmable calculators like the Friden 1155? - Bill On Mon, Dec 9, 2013 at 1:56 PM, Ceruzzi, Paul <CeruzziP@si.edu> wrote:

There was an excellent article in a recent Annals about programming the HP calculators.

I did not own an HP-65 but I did own its successor, the 41C, which had a card reader as an optional extension that plugged in to the top (made the 41C look like the “cone heads” of Saturday Night Live fame—extra brain). Before I had that, I owned an HP25C, which you are correct cost a fortune (for a young graduate student) in the 1970s, but I programmed the hell out of it. The key to your research is a newsletter published by the HP-65 Users Club, called “PPC Journal.” In it on a regular basis was an “HP-25 library,” with software generated mainly by an engineer named Jim Davidson. The amount of effort he put into that library was phenomenal, and it really transformed the machine. This was all distributed free. If HP had to pay a salary to get that software written, it would have sucked all the profit margins from the machine. (Although the calculators were indeed expensive, they were cheap compared to the other products that HP sold, so HP really had to control costs). The software provided by HP as part of their library was lousy by comparison, not because the HP programmers were bad, but because they lacked the fanatical dedication and crazy obsessive-compulsion of the PPC users’ group. We’d spend days just to shorten a program by 2 keystrokes, and when we did, we’d broadcast it to the world.

I think we all contributed for the fun and excitement of it, not for financial gain.

The HP-25 had only 49 steps, but it did have a fairly sophisticated conditional branch capability, which led to one journalist calling it the world’s smallest computer (not in size but in theory). That led to all sorts of philosophical discussions of the distinction between a calculator and computer, some of which sound quaint today. Anyway, a conditional branch is a key to “Turing complete,” and the debate later surfaced over the Harvard Mark I, ENIAC, and Zuse Z3 (the latter did not have conditional branch and was not Turing complete, in spite of what some have asserted).

Don’t start me on RPN! Suffice it to say that I cannot use a calculator (or calculator app on a phone) that does not use it.

The HP-25 had only 49 steps, IIRC, so keying in the programs was fairly simple. I do not recall swapping chewing-gum sized cards for the 41C, but I do recall keying in long sequences of code.

Paul E. Ceruzzi

Chair, Division of Space History National Air & Space Museum MRC 311; PO Box 37012 Washington, DC 20013-7012 202-633-2414 <http://www.nasm.si.edu/staffDetail.cfm?staffID=24>

*From:* members-bounces@sigcis.org [mailto:members-bounces@sigcis.org] *On Behalf Of *Michael McGovern *Sent:* Monday, December 09, 2013 11:32 AM *To:* members@sigcis.org *Subject:* [SIGCIS-Members] HP programmable calculators: economy of programmed cards?

Hello all,

I am an MPhil student at Cambridge in the HPS department working on our science museum’s calculator collection (the Francis Hookham Collection of Handheld Calculators) for a short essay. In working through the collection of calculators and associated ephemera, I have become very interested in HP’s programmable calculators, particularly the HP-65 and subsequent developments in which programs could be written stored on magnetic cards, sent to and ordered from a user library, and also purchased in packages from HP. Given the recent de-emphasis on computation as calculation, this is a fascinating instance in which calculation itself helped create a form of social organization; calculators were not about simply crunching numbers but sharing and writing programs.

I was wondering if anyone on this list a) used these calculators and their magnetic cards or b) know of anyone who might be willing to discuss with me. I am trying to answer the following questions about the magnetic cards and these calculators:

1) How common were they to have? HPs were notoriously expensive and their being programmed in RPN may have led certain groups to turn to other companies like TI. I don’t know how much discussing RPN would figure into this account but I am interested in programming language entrenchment/preferences as well.

2) What was the incentive to enter programs into the HP user library? Was it financial? Did people code programs on spare cards and send them to each other? Was it enough to buy the various packs that HP marketed (Statistics, Flight, Medicine, etc.) or was this seen as facile/not trustworthy?

3) If you yourself worked with these HP calculators with magnetic card readers in the ‘70s and ‘80s, where were you working and to what extent was it desirable to shop for programs rather than simply writing them yourself? I am interested in how different calculators were used infrastructurally but also understand that it was often a source of personal satisfaction and intrigue, as can be seen in the case of Francis Hookham who collected so many calculators!

Thanks so much for hearing me out and I hope to hear from some of you!

Sincerely,

Mikey McGovern

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