Enter RPN: Recognizing HP-12C Variants

Motivation

HP-12C, front side, 1985

Given the long history of the original 1981 version of the HP-12C and its many descendants, it is not easy for a collector to know instantly what they are looking at without having long experience with the whole family. The information needed for teasing all the details apart is available online, but nowhere have I found it all collected in a single place. For lack of a better alternative, this article aims to be that place.

My focus here is on externally visible signs, especially those visible in a photograph on a for-sale forum. For those lucky enough to be able to touch the item prior to purchase, I do suggest a few tests you can make without irritating the seller badly enough to endanger the sale. Completely out of bounds are any destructive tests, even one so mild as peeling off the feet to give access to the case-back screws. Our working premise here is that you are unlikely to carry the argument by pointing out, “But I can just rubber-cement them back on, easy!”

Versions

The HP-12C Classic

Maintaining an electronic device in continuous production status since 1981 necessitates hardware redesigns to track the ever-changing technology landscape, some of which have resulted in externally visible signs. Other changes range from the purely cosmetic to major product-market fit adjustments. The key ones relevant to collectors are:

Variant	Distinction
original	Launch product in the “Voyager” series; everything below descends from this
3 V Nut	CMOSC Nut chip redesigned atop a lower-voltage standard silicon process; 3×LR44¹ → 1×CR2032
ARM (v1)	Nut emulated atop an ARM processor;² RS-232-based pogo port³
30th Anniv.	Released alongside 15c Limited Edition, but with 12C firmware and styling
ARM (v2)	Nut emulated atop a newer ARM processor;⁴ USB-based pogo port³
Euro	Manufactured, sold, and supported under license by external companies⁵

Because these all have a distinctive gold-tinted display bezel, they’re often called “Gold” 12Cs in for-sale forum postings even though HP’s marketing department never used that name. The single most reliable distinguishing mark is the embossed emblem in the upper right corner of the display bezel.

HP 12c Platinum

In 2003, HP released a rethought version with a new look, in step with their corporate branding at the time.

These wear a generic “HP” emblem, with the “12c” product name painted onto the bezel, with that distinctive lowercase letter.⁶

HP did not limit themselves to purely cosmetic changes. They also added an algebraic mode to their RPN classic, expanded the HP-12C’s tight 99-step program space to a comparatively spacious 400 steps — requiring 3-digit addresses in GTO commands — and added several more registers.

Because the first Platinum came out after HP switched to a standard silicon process, none ever shipped with a 3-cell button battery¹ compartment. The initial version used a single CR2032 cell, a design decision they stuck with for five years.

Variant	Distinction
blue-back	Silver-and-blue design; semi-rare because unpopular, which is why it was replaced with…
parens	Adds g-shifted parentheses to `STO` and `RCL` for ALG mode, plus undo & backspace
Prestige	Special gold-colored made-in-Brazil run for the South American market; rare!
25th Anniv.	Silver-on-black debut, with “parens” internals and cursive script accented externals
single-cell	25th AE sans special cosmetics, released after the anniversary year
2×CR2032	Parallel coin cells for improved program retention on change-out, longer life

External Distinctive Attributes

The fastest way to recognize each type is:

Variant	Photograph	Distinctive Attributes
HP-12C “original” (1981)		Double-shot key caps; later production units may have visible “echoes” of other keys due to worn molds;⁷ 3-cell button battery;¹ 1980s/1990s date-coded serial number heat-stamped into the beveled upper edge of case back; no P/N on the orange retail box I have here
HP-12C “Malay” (1990)	[n/a]	First version with painted legends on the keys instead of double-shot molds.⁸ These have an `M` country code in the middle of the serial number until 2000, when the scheme shifted to use an `MY` prefix instead. Reports of `M` = “Mexico” are likely incorrect, confused for pre-2001 Malaysian-made units.⁹
HP-12C “3 V Nut” (2001)		Painted legends on key caps regardless of origin, orange f-shifted text, not gold; 1×CR2032 coin cell powering the Nut redesign on a standard silicon process, necessitating a larger battery door; serial number is now a sticker on the back; P/N “12c” followed by a language code¹⁰
Platinum “blue-back” (2003)		Semi-rare redesign of 12C with silver faceplate, dark blue plastic housing, and “hp 12c platinum financial calculator” printed between display and blue “hp” badge; adds `RPN` above (f-shifted) `CHS` key, `ALG` above `EEX`, and `=` on `ENTER`, requiring `LAST𝑥` to move to `+` key; single CR2032; adds new-style self-test menu; its self-check reports Ver 01 sans dates; P/N F2232A
Platinum “parens” (2005)		Same silver-on-blue design, but added the blue (g-shifted) parens on the `STO` and `RCL` keys to quell ALG user complaints; also adds undo on the `÷` key and backspace on the `-` key; added two additional functions to the new-style self-check menu; the self-check item reports checksum 564Ah and Ver 02 but no release date; hardware copyright C 2004 hP; produced into 2006
Platinum “Prestige” (2006)	[n/a]	Same internals as a “parens” Platinum and similar externals, but the bezel and face-plate are gold-tinted, à la HP-12C; bezel text changed to “HP 12c Prestige Financial Calculator;” made exclusively in Brazil for the Latin American high finance market; produced into 2008 for certain, but I have one report saying 2014; P/N F2233A; rare!
Platinum “25th Anniv” (2006)		Introduced the silver-and-black design language used on all later Platinums; this initial run features “25th Anniversary Edition” script to the right of the display under the “HP” badge and similar script on back, plus “1981-2006”; package included a black leather case with a magnetic-closure top flap, stamped “25th Anniversary Edition”
Platinum “single-cell” (2007)		Same hardware and firmware as the 25th Anniversary Edition, but with the special script removed and the leather magnet-flap case replaced with a cheaper slip case; P/N F2231A; produced into 2008, when…
Platinum “2×CR2032” (2008)		…single coin cell augmented with a second in parallel for longer run time and greater resilience of the continuous memory during battery changes; blank spot where the pogo port³ appears in the HP-12C ARM models; same firmware report as for all prior Ver 02 models, but P/N now F2231AA
HP-12C “ARM (v1)” (2008)		12C line gleans the 2×CR2032 and new-style self-test menu from the Platinum, which reports copyright C 2008 hP for the new hardware; adds an RS-232-based pogo port³ between the coin cells for programming the new ARM processor using the official SDK; the 2014 unit depicted here has firmware checksum E1E1h, released 2012-04-03; P/N F2230A
HP-12C “30th Anniv” (2011)		Same idea as 25th but atop a classic gold 12C base with 2008 ARM v1 internals; new-style self-check reports firmware checksum A3A3h from 2009-07-02; “30th Anniversary Edition” script to right of display, under “HP 12C” badge; in place of a serial number sticker, there is a 5-digit “Limited Edition Number” laser-etched on the metal back plate, 1 of 40k
HP-12C “ARM (v2)” (2015)		“Rev2” text on the back, with the self-check reporting 2015-01-08 firmware, checksum 0F0Fh; same 2×CR2032 battery door with pogo port³ as in the 2008 design, but it’s now USB-based; despite all these changes, the self-check continues to report C 2008 hP for the hardware
HP-12C “Euro” (2022)		Adds a screw to hold the battery door shut per Australian regulations.⁵ “Rev2” on the back is gone, as is the “HEWLETT•PACKARD” branding on the front.¹¹ This exemplar is typical in being “Made in Philippines.” Firmware checksum changes to D1D1h, release 2015-01-30; P/N “HP-12c”

P/N is the product number, printed above or below the UPC barcode on the back or side of the retail package. It does not appear on the calculator itself, nor in the manual, that I have ever seen. I include it to aid identifying new-in-box items.

The most reliable way I know of to tell the 2008 and 2015 ARM versions apart — short of resorting to the firmware version check — is to look for the minuscule “Rev2” text on the back of the newer design. From the front, they’re all but identical, and from the back, the other signs are less reliable, such as the change in the HP logo styling from the 2008-era “invent” exhortation to the plain round “hp” one in 2015.

This detail can be important. Both have a pogo port³ between the cells, but they’re electrically incompatible since the older design is based on RS-232, while the newer one is based on USB. The “Rev2” text did get taken off in 2022, but that’s fine because one then has the screwed-down battery door to diagnose which type of programming port it must have.

The Single-Digit Kabbalah

Starting in 2001, HP switched from heat-stamping 2-digit year codes on the enclosure’s back — offsets from 1960, up on the beveled edge — to printing stickers with single-digit year codes. While this means you can find used units whose sticker has gone missing, our concern here is different: the possible ambiguity arising from the loss of that second digit.

One might suppose that a market-leading company freshly emerged from the Y2K trauma the year prior to this ill-considered decision (2001) would prefer to lengthen a 2-digit year code rather than shorten it, but alas, no, not in this instance. One wonders which bean-counter got promoted for reducing the amount of money spent on thermal-printed sticker material.

The justification must have been, “No calculator design lasts longer than a decade,” and with the HP-12C at least, that remains true. The longest it has gone without an externally visible design change is seven years, a pattern which has repeated three times since this move to single-digit year codes: 2001-2008, 2008-2015, and 2015-2022.

There is reason to hope for a fourth such design cue, because as of the current (2022) design, they’ve switched from individually numbered calculators to lot numbers, but the scheme appears to encode year and week. I have two “Euros” here, one of which I know for a fact was made in 2025 and bears the label L/NO. 9CJ514, which I take to mean that it was made in the 14th week of that year. My second data point fails to falsify this hypothesis: its 9CJ251 label suggests a manufacturing date around Christmas 2022, which is consistent with the screwed-down battery door. While I also bought that one in 2025 — a few months prior to the first — its low sale price suggested NOS the seller wanted to move. (The “2022” back-side shot above is of that second unit.)

If you can provide a lot number and a solid date of purchase for a brand-new unit, I want to hear about it!¹² Additional confirmatory data would firm up this Yww hypothesis, but I will also take conflicting data, provided it has good provenance.

The Platinum Puzzle

All this becomes much worse when it comes to the stock Platinum line, where they used that single-digit year code over a 14-year span in which the external appearance of the units varied little. How does one disambiguate the possibilities?

We can start by bookending that range with these major distinguishing cases:

Screwed-down battery door: Made in 2022 at the earliest.¹³
Silver-on-black, but single-wide CR2032 coin cell door: No earlier than 2006, possibly as late as 2008.
Silver faceplate, dark blue plastic back: Either Ver 01 or initial Ver 02 Platinum model, 2003-2006.

Failing all those checks leaves us with a silver-and-black Platinum with a screwless dual CR2032 battery door, landing us in that troublesome 2008-2022 range. The possible year code interpretations are:

Code	Possible Years
0	2010 or 2020; cannot be 2000, as that predates the Platinum
1	2011 or 2021; cannot be 2001 by the same logic
2	likely 2012, but could be final 2022 production, pre door screw
3	can only be 2013; other tests catch the 2003 and 2023 cases
4	can only be 2014; other tests catch the 2004 and 2024 cases
5	can only be 2015; other tests catch the 2005 and 2025 cases
6	can only be 2016; other tests catch the 2006 and 2026 cases
7	can only be 2017; other tests catch the 2007 and 2027 cases
8	could be first-year (2008) 2×CR2032 production, but more likely 2018
9	2009 or 2019

It is possible to modify an older 2×CR2032 unit’s screwless door to make it fit a new-production machine. There's a securing tab in the wrong location to allow it to click closed as-is, but it can be Dremeled flat, as may be done by one sufficiently motivated to have a screwless door. For those willing to spend a bit of money on the problem and who do not mind the look of 3D-printed parts, there are replacement doors without the screw available from The Calculator Store.

I tell you these things here because it can affect proper identification of a unit. When it is important to be certain, open the battery door and check for a U-shaped slot molded around the screw hole, meant to assist the user in re-centering it properly, the better to avoid munging the threads in those rare instances where a battery change is necessary. The older designs also have a screw roughly in this location, but entirely behind the door, centered about 2 mm to the right. On these, the surrounding plastic is flat because it’s a fifth case-fastening screw, not meant to be removed by the end user, much less re-fastened blind, with the hole behind a closed door.

You might be tempted to make an inference based on the “2004” copyright notice in the firmware self-check, especially if your single-digit year code happens to be in the 4-9 range. That must mean 2004-2009, right, because why, oh why would they still be using the same firmware in 2014-2019? Oh, but they can, and did! I am not aware of any Platinum upgrade past the Ver 02 referenced above; 2004 is the most recent. All other 12-series firmware you can find is for the ARM-based variants of the classic HP-12C.

Manufacturing Origins

What is far more useful in disambiguating these single-year codes is this table of serial number prefixes:

Code	Country	Factory	First…	…and Final Production Year
CN¹⁴	China	first	1995?	2004?
CNA	China	Kinpo	2001	ongoing as of 2025.09
CNG	China	??	2004?	2008?
3CD¹⁵	China	??	2016?	2016?
4CY¹⁶	China	Besta	2004?	ongoing as of 2025.09
PHA	Philippines	??	2015	2022?
9CJ	Philippines	??	2022	ongoing as of 2025.09

Alas, this is all I have been able to find as an HP outsider, but it’s not entirely useless as-is.

Years followed by question marks indicate information found by watching for actual units in the wild. Take CNG: this thread tells us that this factory was putting out units so marked in 2005, and the 2008 ceiling comes from a unit I own with a CNG8 prefix, for which I have ruled out a 2018 manufacturing year. Presuming continuous use of the same facility over this span, these data points give us a known window, but one which we might later learn to be wider than presently stated.

References to “Royal Consumer Information Products” or “MORAVIA Consulting spol. s r.o.” on the packaging or in the collateral material indicate manufacturing in or after 2021. These typically follow the lot numbering scheme above, but occasionally an oddball unit will pop up with a short label like C1G210, obeying no long-lasting scheme. The leading “C” confirms the “Made in China” declaration on the metal back-plate, and the 210 might be a Yww date code meaning the 10th week of 2022.

The “Rev2” photo above is one such unit. Because it is a 12C with a screwless door, there are only two possibilities for when it was made: in 2021, or early enough in 2022 that they had not yet gotten the new door design into manufacturing. Any earlier, I would not have found Moravia’s name in the manual; any later, I would have found a screwed-down battery door and a L/NO. style lot number sticker. Thus my best working hypothesis explaining this cryptic sticker: it is a relic of the interim period between Moravia/Royal taking over joint manufacturing from HP proper and them arranging the new screwed-down battery door design, where the present lot numbering scheme came into play. Further evidence in support of this hypothesis is that these C1Gyww units still have the “HEWLETT•PACKARD” branding at the bottom of the face-plate; that disappeared in 2022.

Mine has one other distinguishing quirk: it doesn’t respond to the .-ON combo to swap the digit separator and decimal mark. The firmware reports checksum 0F0Fh, released 2015-01-08. I then have a unit with a normal serial number sticker which does respond to this configuration combo, with checksum D1D1h, released 2015-01-30. Clearly they made a bug fix in that span of weeks, yet a prior knowledge of buggy firmware cannot be the reason for this odd serial number sticker; surely they would have held it back for the coming fix and reflashed it before sending it out.

Strange.

Another odd distinctive characteristic is finding a taller % key symbol than was used on the neighboring Δ% and %T keys. I have seen multiple independent reports of this online, and I personally have two Chinese units with this characteristic, one of which was manufactured by Inventec Besta in 2014. (It is the “ARM v1” unit whose backside is depicted above.) The other is the one with that odd C1G210 lot number sticker, believed by the signs detailed above to be made in 2022, but lacking a proper manufacturer’s code, I cannot say whether it was also made by Besta. If this oddity extends further in time and/or space, I will need data to support it.

On that note, I hereby solicit submissions¹² from anyone who has authoritative data along the many lines of argument and inference developed above. I cannot guarantee to publish any of it, if only because I first need to have reason to believe it will help narrow things down for a broad class of readers. Long as this document is, I do not wish to make it longer without somehow making it more useful.

Putting It All Together

Say we’re looking at a unit with a serial number beginning “PHA5.” The data above tells us it’s Filipino-made, in “facility A,” whatever that may mean. It further tells us that the “5” cannot mean 2005, an inference we can double-check by the absence of a single-wide battery door. We can further rule out 2025 since you would see the screw on the battery door or the U-shaped slot in the case back to accept it. Absent those clues, the production year must be 2015.

Benchmarks

Performance can be another way to cross-check the hardware design, but we must be careful in establishing our baselines.¹⁷

The most convenient and reliable method available to the discerning calculator buyer needing to make a quick hands-on determination is the built-in self-check. The problem is, there are two different self-checks on most models, and they run at different speeds! I have no proof, but my guess is that the faster one runs directly on the host CPU, whereas the slower one runs in an emulator of the original design’s CPU. All Platinums support both flavors, and HP added the new-style check to the original 12C at the next design change after the Platinum’s introduction, when they moved from the 3 V Nut CPU design to the v1 emulation of Nut on ARM.

I will therefore report both results where available:

Family	Year	Variant	New-Style	Old-Style
HP-12C	1981	original	n/a	13 sec.
HP-12C	2001	3 V Nut	n/a	13 sec.
Platinum	2003	original	17 sec.	20 sec.
Platinum	2005	parens	4.5 sec.	27 sec.
Platinum	2006	25th Anniv.	4.5 sec.	27 sec.
Platinum	2007	single-cell	4.5 sec.	27 sec.
Platinum	2007	2×CR2032	4.5 sec.	27 sec.
HP-12C	2008	ARM (v1)	instant	< 1 sec.
HP-12C	2011	30th Anniv.	instant	< 1 sec.
HP-12C	2015	ARM (v2)	instant	< 1 sec.
HP-12C	2022	Euro	instant	< 1 sec.

The difference between the sub-second and “instant” results amounts to whether I saw the running message appear or not. In cases where it’s up long enough to blink, I used a manual stopwatch to produce the numbers above, rounded to half-second accuracy, my best estimate of my own reaction time. Counting blinks is unreliable, as the blink rate can (and does) vary over the course of the test in certain cases.

More precise results doubtless exist elsewhere, but I doubt having millisecond-scale data would help.

URLs

The HP calculator division did not begin putting their web URL on the back of their calculators until 2001.¹⁸ It likely appeared earlier in manuals and retail collateral, but that is not our focus here. What does attract our attention is that because the presentation and exact address used has changed several times, one may use it as a rough sort of date code given this correlation table:

First Year	Last Year	URL Format
2001	2006	http://www.hp.com/calculators/
2003	2003?	http://www.hp-calculators.com¹⁹
2005	2005	www.hp.com/calculators
2005	2021	www.hp.com/calculators
2021	present	www.hpofficesupply.com (Royal)
2021	present	www.hpcalcs.com (Moravia main)
2022	2022	www.hpcals.com (Moravia typo²⁰)

The serif font used in some entries is a rough attempt to mimic the styling used by HP at the time. I find that detail helpful because, as a rule, HP uses sans serif everywhere except in these URLs, but then only sometimes! Serifs are therefore diagnostic when present.

Years given with a question mark are indefinite and may move away from the mid-point as more data turns up. (First year can only move down from where it is shown now, last year can only move up.)

The Shifted-OFF Non-Difference

Above, I chose to leave out one addition HP made to the Platinum line: an OFF label above the ON key. Because it is in the same font and color as for the f-shifted functions, the implication is that the ON key is no longer a toggle as it was in the classic HP-12C line. Based on tests here on several units, that is very much not the case!

My best guess as to the functional import of this label is purely to reassure users, on one of two grounds:

You do not have to wait out the idle timeout before the calculator will return to sipping the micro-scale idle current necessary to maintain the “continuous memory” feature. The label is there to inform the non-manual-reading user that they have the option of turning the calculator off manually, a fact that was not immediately clear with the classic 12C.
Other calculators in HP’s lineup required a shifted ON sequence to turn it off, including the Platinum’s spiritual descendant on the algebraic side of the house, the 10bII. Perhaps this label was meant as a sop to habits developed on these other machines as a result. The best argument I have against this is that g ON also turns off everything from the newest Platinum I have here (2017) down to a 1983-made 12C.

Was rendering this label in the same color and font as the other shifted functions a design mistake? I believe a more charitable explanation is that it saved the cost of a two-pass paint job, as would be needed had they used a neutral shade or a different color for this label.

Because this OFF label is present on all Platinums and absent on all classic 12Cs, it doesn't help us narrow down the manufacturing date for a given unit. The only reason I even included this section is to quell rising "Aha" moments in those who think they have found a diagnostic difference. Sorry; no dice.

Sources

Much of this has been verified from my personal collection. All photographs above are of units I personally own, or at least once did own before sending them on to other homes.

While there are many external sources of information on the world-famous HP-12C product line, I found the following especially helpful in preparing this:

Wikipedia article on the HP-12C. Early versions of this article pulled photos from the HP-12C section of their Wikimedia Commons, before I began replacing them with shots of my own collection; their archive may still be of interest to readers of this article.
The blog Persistent Technology did an article titled, “The Hewlett-Packard HP-12C Financial Calculator: A Contradiction of Modern Technology” which collected much of this information as of a dozen years prior. I have not attempted to make a 2025 update of the article here so much as mined it for back-filling details when other sources failed. There is much of interest in that article which I saw no reason to add here, if only because of the different motivations behind this effort.
Decoding Serial Numbers section of the Collector’s Corner page at The Museum of HP Calculators; searches of the MoHPC Forum turned up some of the detail presented above.

License

^{^ a b c} The initial series of Voyager calculators were powered by three 1.5 V LR44 size cells in series, giving the 4.5 V nominal needed to power the proprietary HP Nut processor at their core. These are sometimes called A76 or “357” cells. This technically constitutes a “battery,” being two or more discrete electrochemical cells connected together in series or parallel. One may therefore say that the Voyagers started out being battery-powered, then went through a phase where they were powered by a single CR2032 coin cell, and are now battery-powered once again, with all production models taking 2⨉CR2032 in parallel. If I catch you describing a single coin cell as a “battery,” I am required to become cross with you in order to maintain my Geek License credentials. Sorry, that’s just how it is.
^{^} Atmel AT91SAM7L128
^{^ a b c d e f} This term is a reference to the 2×3 array of pogo pins used on the programming/debugging connector for later models of these calculators. It is often styled “POGO” even though it is not an acronym. This did not appear in the 12C family until after the move from the HP-proprietary Nut processor, backed by at least three incompatible CPU types: the ARM v1 in 2008-era 12Cs, the ARM v2 in 2015+ 12Cs, and the 6502 core of the Platinum line. Atop this, the 2008 design used RS-232 style 3.3 V TTL signaling, whereas the 2015 design uses proper USB. All of this means that if you find a pogo connector between the two CR2032 coin cells behind the battery door, there are at least three different ways to talk to it, and if you get it wrong, there’s a nonzero chance you will damage your calculator.)
^{^} Atmel ATSAM4LC2CA-AU Cortex-M4
^{^ a b} Moravia Consulting in Europe and Royal Consumer Information Products, Inc. in the USA. I call it the “Euro” version because of the redesign’s source. The actual motivating change is a worldwide shift in safety standards including Reese’s Law in the US and a similar Australian standard, both requiring a secured battery compartment. The intent is to keep children from opening devices and swallowing the coin cells found inside, risking internal injuries, possibly even death. This is also why button cell product packaging is now “child-proof,” requiring scissors to cut open the encapsulating plastic bubble, where older packaging allowed popping them out of the foil backing with normal finger pressure.
^{^} Packaging is a different story, as each year’s fashion came down by corporate marketing decree. I have here a new-in-box “12c” with the original capital-C styling on the actual calculator, making it a classic, not a Platinum.
^{^} Look at the key caps under strong light, from an angle. I have a USA-made 1988 unit here where you can see an echo of the square root symbol bracketing the n key label, e^x under the i key, etc.
^{^} All Malaysian-made units are like this. In the interest of fairness, however, I bought a beat-up MY0-prefixed unit and attempted to remove the legends with every solvent I had ready at hand — isopropyl, acetone, paint thinner… — but I had little luck. The most effective thing was MEK, which worked by melting the key-cap itself! Acetone had more effect on the faceplate’s gold and brown paint than on the orange shift labels or the legends on the key caps. What will work is thousands of fingertip strikes over the course of years, but then, that will also damage the key switches themselves; point is, there's a practical limit on the utility of making the legends more durable.
^{^} This may reflect a bias in what is available on the markets I monitor. Check the “Made in $COUNTRY” text on the back-plate to be certain.
^{^} “ABA” indicates English-language packaging and manuals, “ABB” or “INT” the multi-language international version, and so forth…
^{^} The bold line at the bottom of the calculator’s faceplate now goes all the way across.
^{^ a b} The most direct way to contact me is via the Forum button above. It is a feature of the Fossil software backing this site, which I have enabled purely for discussing the site’s contents, not in a bid to dilute any other community. On that note, I am “tangent” on the MoHPC Forum, where you may instead send me a PM.
^{^} This rule is more useful in the inverse form since the change corresponds with the lot numbering scheme reported above for the HP-12C, which applies equally to the Platinum.
^{^} Mainly seen heat-stamped into pre-Kinpo Chinese units. It differentiates from “CNA” where the “A” indicates HP’s second Chinese factory.
^{^} I have only seen this code once, on an ARM v2 HP-12C made in China, making the “6” year code digit = 2016.
^{^} My completely unsubstantiated pet theory is that this code stands for “4th Chinese factory, Yīngyèdá Gōngsī, the pinyin spelling of the Chinese parent company of Inventec Besta. Failing that, it is at least a useful mnemonic.
^{^} You can find micro-benchmarks claiming 100× speedups. They are not reporting the same thing tested here.
^{^} This late date may strike you as curious. HP was one of the founding companies of Silicon Valley, thus a very early presence on the pre-Internet ARPANet, long before DNS was first designed, back when all an organization had to do to snag a sweet two-character dot-com domain was convince the lone guy who had the job to decide who got what. (The late, great Jon Postel.) Why then — given this long history preceding the invention of HTTP 0.9 — do we not see an http:// format URL printed on these calculators until 2001? It’s simple: they were still making classic 3⨉LR44 units until then. It wasn’t until the ARM v1 redesign that they were forced to change the back-plate, at last giving them the opportunity they needed to add the URL.
^{^} This domain is presently unregistered, so presuming it did once work, HP stopped renewing its registration at some point. I have only seen this on blue-back Platinum units manufactured in 2003, but I have not yet ruled out the possibility that this oddity extended into 2004 or even into 2005 when it was changed to hp.com on the first “parens” units.
^{^} Admittedly, this is a presumption based on the fact that it has been seen only on first-year screw-door Platinums. There is reason to believe it only appeared in the first prototype run, then was corrected, but I do not have definitive proof for that.