Saturday, 13 April 2013

The Hewlett-Packard HP-12C Financial Calculator
A Contradiction of Modern Technology

My HP-12C collection: current 2013 model (left), 25 year vintage model (right)
The HP-12C financial calculator was launched with its 11C scientific sister in 1981, the same year IBM launched their first PC. This Voyager series expanded to five calculators (10C, 11C, 12C, 15C, 16C), however the HP-12C was the only financial model and today, over 30 years and 15 million units later, remains the only one still in production. With the lifecycle of consumer electronics now measured in months, the HP-12C is truly a contradiction of modern technology. Why?

Some reasons include the rock-solid reputation Hewlett-Packard calculators built up in the 1970’s, the HP-12C’s superb high-contrast LCD, powerful yet easy-to-use business functions, programmability, reliability and exceptional battery life that is measured in years. The HP-12C’s original $150 sticker price gave the financial community a pocket-sized tool that revolutionized the market and defined what remains the de facto standard even today.

No doubt the quirky RPN input and attractive horizontal design contributes to its ongoing popularity, but in reality the HP-12C carved out a niche for itself before the Internet and affordable computing swept through homes and businesses in the 1990’s. Even today, the HP-12C is one of only two calculators approved for CFA (Chartered Financial Analyst) exams.

Another clue to its popularity are the more recent variations. 25th and 30th Anniversary editions marked significant milestones, and the HP-12C Platinum (launched in 2003) added more memory, a faster processor and significantly, the option of switching from RPN to algebraic entry for users brought up outside HP’s rather unique input methodology. Backspace and parentheses keys, and several new functions also differentiate the Platinum from the original HP-12C, which soldiers on alongside its newer brother although now with a faster ARM-based processor (since 2008) running the original code in an emulation environment.

Production started in USA and Singapore initially, joined by Brazil and Malaysia in the 80’s and 90’s. Like almost all electronic consumer goods produced today, the HP-12C and HP-12C Platinum are now produced exclusively in China.

Development and Identification of Different HP-12C Models:

HP designed and manufactured their early calculator processors, with the HP-12C’s original 1LF5-0301 CPU a close variant of the Nut processor used in the HP-41C programmable calculator but running at a slower speed of 220kHz. This CPU was paired with the 1LE2-0308 RAM/ROM/Display Driver (R2D2) chip on a Kapton flexible circuit mounted behind the LCD module and connected to the keyboard PCB. The R2D2 chip had 6K x 10-bit ROM and 43 x 56-bit registers of RAM (approx. 2.3Kbit). The ‘C’ at the end of HP-12C indicates it had continuous memory, a feature first launched by HP with the HP-25C in 1976.

With the expansion of the Voyager family, HP redesigned the HP-12C’s internals, eliminating the flexible circuit by moving the CPU and R2D2 chips to the keyboard PCB. The 1LF5-0301 CPU and R2D2 1LE2-0308 chips were later replaced by the functionally identical 1LM2-0001 and 1LH1-0304 R2D2 chips.

HP was able to combine the CPU and R2D2 chips into the single LQ9-0322 microprocessor. This redesign also required a new LCD with the pin count reduced from 52 to 29 (4:1 instead of 2:1 multiplexing). The LQ9-0322 was later replaced by the 1RR2-0001, still an HP manufactured chip.

HP-12C’s powered by the 1LF5, 1LM2, LQ9 and 1RR2 CPUs are all identifiable by using three 357/LR44 button cell batteries behind a small battery door. The “+, GTO 01” program test loop runs to approximately 500 in 1 minute. (Load 0 1 1 1 in stack).

In the first major redesign since dropping the flexible circuit, HP adopted the Agilent 2AF1-0001 CPU designed to run on lower 3.3Vcc voltage but using the same core as the original CPU’s. (Agilent split off from HP in 1999). This redesign allowed power from a single 2032 battery with production shifting to China.

In 2003 HP launched the single 2032 battery powered HP-12C Platinum, a complete redesign from the standard HP-12C. Using an 8-bit Sunplus SPLB20D 8502 microcontroller with a 6502-compatible processor core similar to the CPU used in the Commodore 64 of the 1980’s, it was initially not much faster than the original and in some calculations was actually slower. It had some bugs and the algebraic implementation was not complete. These early versions can be identified by their silver key surround and lack of parenthesis or backspace keys. Responding to these issues, HP redesigned the Platinum using ROM code derived from the HP 17BII+ and changed the key surround to the tradition black colour, although some versions with silver key surrounds and the updated CPU were made before they switched over to the 25th Anniversary Edition in 2006. This and the Brazilian Prestige version were cosmetic reworks. All Platinum models also benefit from 400 program steps and use a new LCD with taller numbers and contrast control. The standard loop test runs at around 1,400.

In 2009 HP quietly supercharged the HP-12C with an Atmel AT91SAM7L128 microprocessor (based on an ARM 7TDMI 32-bit microprocessor core), running at 30MHz when executing code. The processor runs the HP-12C code in emulation mode delivering performance 50-150 times faster than the original, and 10-20 times faster than the Platinum version. The ARM driven HP-12C is easily identified by running on two 2032 batteries. This version is the basis of the 30th Anniversary Edition (2011) and is also informally known as the HP-12C+. Loop tests exceed 30,000. The faster clock speed means battery life is significantly shorter that previous versions.

In what appears to be an effort to streamline production, HP adopted the same two battery rear housing for the HP-12C Platinum in 2010, but using the same 8-bit 8502 Sunplus microcontroller as in the single battery Platinum version. The 6-pin connector (for ROM programming) found in the ARM version HP-12C is not present in these Platinum versions.

Quality Variations

The first HP-12C units were manufactured in the USA and Singapore, with Brazil joining production from 1984. These early models established a reputation for good build quality including their double-mounded keys (not printed). Early production used a metal logo badge while all later models use a painted plastic logo. Early flexible circuit models can suffer from track failure years later compared to the single board versions. Brazil production ended in 1992 due to legislative issues. Singapore production ended around 1996 with US production ending in 2003.

Malaysia manufacture started in 1990 and continued until 1999 when it transferred to China due to political instability in Malaysia. Malaysia manufactured units were the first to use painted keys. Early Chinese production still used 3 batteries and had the same internal construction as units made in Malaysia including the painted keys.

The early single-battery Chinese units had a reputation of inferior quality however the more recent 2-battery versions (both ARM and Platinum) have better quality. Most people agree that the original 3-battery versions from the USA are the best in terms of quality. The early single-battery Platinum versions are generally considered to have the poorest quality with people reporting lose keys that do not always register.

While processing speeds have dramatically increased over the last 30 years, one element that appears to have moved backwards is the LCD. The original HP-12C had extremely good contrast on a clear, almost white panel.  Later HP-12C units, including the current ARM powered units, have a more yellow cast to the LCD, reducing the contrast. However, the Platinum versions are criticized the most for their displays that have nowhere near the contrast or readability of the original, even though they have adjustable contrast.

HP-12C production has been in China exclusively for the last ten years, with production today taking place in two factories, Kimpo Electronics and Invertec Appliance. Some opinion is that units from Kimpo are better. Production from Kimpo can be identified with the ‘CNA’ serial number prefix, while Invertec units have a ‘4CY’ prefix.


  1. Very informative!

    I think the P-12C survives because of it's great design and elegant packaging combined with a simple interface. Financial guys don't want to waste time messing with menus and cryptic instructions. They want to be able to get answers on the fly without a lot of fuss. Also want something that feels well made and durable.

    While there is no question the Voyager series is better made than the Spice series, I have to say my favorite is the predecessor to the 12C, the HP-38C, which is almost functionally identical ( but without the bond and depreciation functions). Despite its flimsy packaging, I like the 38C's vertical design so I can use it in my hand. However, with it's flimsy design and terrible battery performance, it's no wonder it was replaced by the HP-12C.

    It seems HP found a winner in the 12C and it reminds people of the great company HP used to be.

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