HP-15C#DM15

The HP-15C is a high-end scientific pocket calculator with a root-solver and numerical integration. A member of Hewlett-Packard Voyager series of programmable calculators, it was produced between 1982 and 1989. The calculator is able to handle complex numbers and matrix operations. Although out of production, its popularity has led to high prices on the used market. The HP-15C was a replacement for the HP-34C. The 15C used bulk CMOS technology for its processor, resulting in very low power consumption.

After showing a prototype labelled HP 15c+{{cite web |url=http://www.hpmuseum.org/forum/thread-7791-post-68608.html#pid68608 |title=HP-15C+ Prototype? |website=Hpmuseum.org |access-date=2017-12-10}} at the HHC 2010, HP announced the HP 15C Limited Edition (NW250AA) on 1 September 2011. It is based on a flashable controller utilizing the same ARM7TDMI core already used in the 2008 revision of the 12C but in a different package,{{cite web |url=http://www.hp.com/hpinfo/newsroom/press/2011/110901xa.html |title=Filter News Results - HP Newsroom HP Press Releases |website=Hp.com |access-date=2017-12-10}} an Atmel AT91SAM7L128-AU{{cite web |url=http://www.finetune.co.jp/~lyuka/interests/calc/hp15cle/ |title=HP 15C Limited Edition |website=Finetune.co.jp |access-date=2017-12-10}}{{cite web |url=http://media.digikey.com/pdf/PCNs/Atmel/RE133101_AT91SAM7Lxx_Obs.pdf |title=Product End-of-Life (EOL) Notification |website=Media.digikey.com |access-date=2017-12-10}}{{cite web |url=http://media.digikey.com/pdf/PCNs/Atmel/SE133406A_Obs.pdf |title=Product End-of-Life (EOL) Notification |website=Media.digikey.com |access-date=2017-12-10}}{{cite web |url=http://media.digikey.com/pdf/PCNs/Atmel/RE150402.pdf |title=Product End-of-Life (EOL) Notification |website=Media.digikey.com |access-date=2017-12-10}} running an emulator written by Cyrille de Brébisson to execute the old HP Nut code much faster than on the original hardware. The calculator was released alongside the HP 12c 30th Anniversary Edition. This model is powered by two CR2032 batteries, and can easily be differentiated from the original model by the "Limited Edition" script below the company logo as well as the black text on brushed metal back label, as opposed to the white text on black of the original. The power consumption of the processor is greater than that of the original HP-15C, as HP did not use the same technology in any of the future models.

In May 2023, a HP 15C Collector's Edition was announced{{cite web |title=New: HP 15C Collectors Edition |date=2023-05-02 |author-first=Klaas |author-last=Kuperus |url=https://www.hpmuseum.org/forum/thread-19886.html |access-date=2023-08-10 |url-status=live |archive-url=https://web.archive.org/web/20230809234234/https://www.hpmuseum.org/forum/thread-19886.html |archive-date=2023-08-09}} and was released in July 2023 by the HP Development Company, L.P.'s licensees Moravia Consulting spol. s r.o. and Royal Consumer Information Products, Inc.{{cite web |title=HP Calculator Division |url=https://hpcalcs.com/product/hp-15c-collectors-edition/ |access-date=2023-07-05}}{{cite web |title=Eduwinkel |url=https://www.eduwinkel.nl/hp-15c-collectors-edition-calculator.html |access-date=2023-07-05}} The calculator is manufactured in the Philippines. It supports up to 672 steps for programs and up to 99 registers. The initial firmware incorporates fixes for the known bugs from previous models (as shown below) and others;{{cite web |url=https://www.hpmuseum.org/forum/thread-19886-post-172018.html#pid172018 |title=The Museum of HP Calculators, post from contributing developer |access-date=2023-08-03}} it is emulated on the same CPU{{cite web |url=https://www.hpmuseum.org/forum/thread-19886-post-175417.html#pid175417 |title=The Museum of HP Calculators, vendor's post |access-date=2023-08-03}} as the 2015 and 2022 variants of the HP-12C, the Microchip ATSAM4LC2CA (ARM Cortex-M4).{{cite web |url=http://www.brouhaha.com/~eric/hpcalc/voyager/variants.html |title=HP Voyager Calculator Variants |website=Brouhaha.com |access-date=2023-08-03}} The calculator is also powered by two CR2032 batteries.

The test menu (Off, {{key|g|ENTER|ON}}) officially offers three choices. A fourth choice ({{key|4}}) is undocumented and permits to enter two hidden modes: "15.2" (more memory, but with some limitations like 8×8 inversion matrices and three-digit step number display) and "16" (emulating a HP-16C).

Unlike the earlier editions, the Collectors Edition does hot have the "Hewlett-Packard" text along the bottom left of the panel and is a slightly darker shade of brown than the original.

HP-15C:

• CHS stack lift bug (and fix)
• The non-responsive reset procedure documented in the 15C manual had the side effect of rotating the X register by 22 bits which could then be used to perform synthetic programming.{{cite web |title=HP-15C Synthetics |date=2023-01-30 |orig-date=2004 |author-first=Eric L. "Brouhaha" |author-last=Smith |url=http://www.brouhaha.com/~eric/hpcalc/hp15c/tennant83.html |access-date=2023-09-25 |url-status=live |archive-url=https://web.archive.org/web/20230925194842/http://www.brouhaha.com/~eric/hpcalc/hp15c/tennant83.html |archive-date=2023-09-25}}{{cite web |title=HP 15C Synthetics and Synthetic Programming |website=YouTube |date=7 March 2022 |language=en |url=https://www.youtube.com/watch?v=7b6rQtSNnqY |access-date=2022-08-10}}

HP-15C Limited Edition:{{cite web |title=HP-15C LE (Limited Edition) Bug Reports |author-first=Katie |author-last=Wasserman |date=2011-12-26 |orig-year=2011-09-16 |url=http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=1089 |access-date=2017-12-20 |url-status=live |archive-url=https://web.archive.org/web/20171220064345/http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=1089 |archive-date=2017-12-20}}

• One of the more significant bugs in the released firmware version (dated 2011-04-15 in the self-test) is that PSE only works once in a program and subsequently blanks the display until the program stops or is stopped. Downgrading the firmware resolves the PSE bug,{{citation |title=HP 15C LE PSE / Pause Bug Fix | date=4 July 2022 |url=https://www.youtube.com/watch?v=y5EKQJ62RlU |language=en |access-date=2022-08-05}} however, other bugs will also be reintroduced.
• The original HP-15C self-test keystrokes do not work with the HP-15C LE and can corrupt memory contents. Although a new functional self-test procedure was added, the original manual did not document it.{{citation |title=HP 15C Limited Edition LE Scientific Calculator Self-tests | date=5 November 2021 |url=https://www.youtube.com/watch?v=QEvuOJTfuaw |language=en |access-date=2022-08-05}}

HP-15C Collector's Edition:

• The bugs above and others have been fixed in the firmware, or in the case of the non-functional self-test procedure, instructions to switch to the new self-test are included in the accompanying documentation. There are a number of bugs and shortcomings in the undocumented "15.2" and "16" modes,https://www.hpmuseum.org/forum/thread-19886-page-16.html most of which were fixed by a community member by October 2023.{{cite web | url=https://www.hpmuseum.org/forum/thread-19886-post-179437.html#pid179437 | title=NEW: HP 15C Collectors Edition }}{{cite web | url=https://www.hpmuseum.org/forum/thread-19458.html | title=WIP: 16C firmware hack for more memory }}{{Cite web |title=Modifying firmware to fix the DEC bug - TheCalculatorStore |url=https://www.thecalculatorstore.com/c/hp15c/how-to-use-the-programming-cable/modifying-firmware-to-fix-the-dec-bug |access-date=2024-09-07 |website=www.thecalculatorstore.com}}
• Pressing and holding a label key after GSB, or pressing and holding A through E in user mode, shows the target step on the original HP-15C but runs the step immediately on the HP-15C CE.https://www.hpmuseum.org/forum/thread-22535-post-193777.html#pid193777

An official PC emulator for the 15C is available as freeware from Hewlett-Packard.{{cite web |title=Emulateurs |language=fr |date=2014 |url=http://www.calculatrices-hp.com/index.php?page=emulateurs |access-date=2017-09-17 |url-status=dead |archive-url=https://web.archive.org/web/20170917223308/http://www.calculatrices-hp.com/index.php?page=emulateurs |archive-date=2017-09-17}}{{cite web |title=HP 15C Virtual Calculator |publisher=Hewlett-Packard |date=2012-11-29 |url=http://www.calculatrices-hp.com/uploads/emulateurs/HP_15C_Virtual_Calculator_2012_11_29.zip |access-date=2017-09-17 |url-status=dead |archive-url=https://web.archive.org/web/20160608225015/http://www.calculatrices-hp.com/uploads/emulateurs/HP_15C_Virtual_Calculator_2012_11_29.zip |archive-date=2016-06-08}}

There are many calculators simulating software, imitating various HP calculators.{{Cite web |title=HP Calculator Simulations |url=https://www.hpmuseum.org/simulate/simulate.htm |access-date=2024-09-06 |website=www.hpmuseum.org}}{{Cite web |title=OTHER Files |url=https://www.hpcalc.org/other/ |access-date=2024-09-06 |website=www.hpcalc.org}}{{Cite web |title=RPN Tutorial |url=https://hansklav.home.xs4all.nl/rpn/ |access-date=2024-09-06 |website=hansklav.home.xs4all.nl}}

File:Hewlett Packard 15C Standard Edition.jpg|HP-15C from the 1980s

File:HP-15C Calculator Backside (edited, changed perspective to plan).jpg|The rear side of HP-15C

File:HP-15C Collector's Edition.jpg|HP-15C Collector's Edition

• List of Hewlett-Packard products: Pocket calculators
• HP calculators

{{reflist}}

• {{cite book |title=Hewlett-Packard HP-15C Owner's Handbook |publisher=Hewlett-Packard Development Company, LP. |date=September 2011 |version=2.4 |id=00015-90001 |url=http://www.hp.com/ctg/Manual/c03030589.pdf |access-date=2015-12-05 |url-status=live |archive-url=https://web.archive.org/web/20170917224935/http://www.hp.com/ctg/Manual/c03030589.pdf |archive-date=2017-09-17}}
• {{cite book |title=Hewlett-Packard HP-15C Advanced Functions Handbook |publisher=Hewlett-Packard Company, Corvallis Division |date=August 1982 |id=00015-90011 |url=http://hp15c.org/hp15cAdvanced.pdf |access-date=2015-12-05 |url-status=live |archive-url=https://web.archive.org/web/20170917224950/http://hp15c.org/hp15cAdvanced.pdf |archive-date=2017-09-17}}
• {{cite book |title=Hewlett-Packard HP-15C Advanced Functions Handbook |publisher=Hewlett-Packard Development Company, LP. |date=2012 |orig-date=1982 |id=00015-90011 |url=http://www.hp.com/ctg/Manual/c03308725.pdf |access-date=2015-12-05 |url-status=live |archive-url=https://web.archive.org/web/20170917224955/http://www.hp.com/ctg/Manual/c03308725.pdf |archive-date=2017-09-17}}
• {{cite book |title=HP 15c Collector's Edition - Scientific Calculator - Owner's Handbook |date=February 2023 |edition=3 |publisher=MORAVIA Consulting spol. s r.o. |url=https://literature.hpcalc.org/official/hp15c-ce-oh-en.pdf |access-date=2023-08-10 |url-status=live |archive-url=https://web.archive.org/web/20230810093104/https://literature.hpcalc.org/official/hp15c-ce-oh-en.pdf |archive-date=2023-08-10}} (1+xi+293+2+1 pages)
• {{cite book |title=HP 15c Collector's Edition - Scientific Calculator - Advanced Functions Handbook |date=July 2023 |edition=3 |publisher=MORAVIA Consulting spol. s r.o. |url=https://literature.hpcalc.org/official/hp15c-ce-afh-en.pdf |access-date=2023-08-11 |url-status=live |archive-url=https://web.archive.org/web/20230811185846/https://literature.hpcalc.org/official/hp15c-ce-afh-en.pdf |archive-date=2023-08-11}} (2+2+222+2 pages)
• {{cite web |date=March 1982 |author-first=Howard W. |author-last=Markstein |title=A look inside Hewlett-Packard's HP-11C |work=Electronic Packaging and Production Magazine |url=http://www.vcalc.net/hp-11.htm |access-date=2023-08-12 |url-status=live |archive-url=https://web.archive.org/web/20170917225028/http://www.vcalc.net/hp-11.htm |archive-date=2017-09-17}}
• {{cite journal |title=Scientific Pocket Calculator Extends Range of Built-in Functions Matrix operations, complex number functions, integration, and equation solving are only some of the numerous preprogrammed capabilities of HP's latest scientific calculator, the HP-15C. |author-first1=Eric A. |author-last1=Evett |author-first2=Paul J. |author-last2=McClellan |author-first3=Joseph "Joe" P. |author-last3=Tanzini |journal=Hewlett-Packard Journal |date=May 1983 |volume=34 |number=5 |publisher=Hewlett-Packard Company |issn=0018-1153 |publication-place=Palo Alto, California, USA |pages=25–35 |url=https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1983-05.pdf |access-date=2023-09-21 |url-status=live |archive-url=https://web.archive.org/web/20230921192321/https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1983-05.pdf |archive-date=2023-09-21}} (11 pages)

• {{cite web |url=http://www.hpmuseum.org/tech10.htm |title=HP 10C Series Technology and Packaging |work=Museum of HP Calculators |author-first=David G. |author-last=Hicks}}
• {{cite web |url=http://www.brouhaha.com/~eric/hpcalc/ |author-first=Eric |author-last=Smith |title=Hewlett-Packard Calculators}}
• {{cite web |url=http://mycalcdb.free.fr/main.php?l=0&id=815 |website=MyCalcDB |title=HP-15C}}
• {{Flickr image inline link|id=6708144099|name=HP-15 Limited Edition (photo)}}
• {{URL|https://www.hpcalc.org/details/9638|HP 15c CE Firmware Update}} (fixing the hidden 16c mod)

{{HP calculators}}

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15C