HP-12C

There were at least eight hardware revisions of the HP-12C since 1981 (including one special issue). Over its lifespan, the proprietary silicon on sapphire HP Nut (originally the 1LF5, then 1LM2)[1] processor's technology has been redesigned to integrate all the circuitry into a single chip (first the 1LQ9, then 1RR2)[1] and to refresh the manufacturing process (as the foundry could no longer manufacture the necessary chips, having moved on to making higher-density chips). However, HP's market research found in the late 1980s that users did not trust results obtained too quickly and so the CPU speed was never improved from the original 884 kHz, but the speed could be increased by a user modification.[6] In the late 1990s, the CPU was changed to a 3 V process (Agilent 2AF1-0001,[1] later a Marvell 2AF1-0002[7]) and the battery was therefore changed to a single CR2032 cell replacing the three LR44 cells previously used (F1637A).

In 2008, HP modified the design to use an Atmel AT91SAM7L128[1][8][9][10][11] processor with ARM7TDMI core running a software emulator of the previous Nut processor, written by Cyrille de Brébisson, in order to execute an image of the former Nut-based firmware in it. This has brought advanced possibilities such as flashing new firmware, not previously possible. HP also released a software development kit (SDK), making it possible to make new and custom operating systems.[12][13] The calculator ran 60-90 times faster on most benchmark operations. This version (F2230A) was colloquially known as the "HP-12C+", although HP did not market it as a different product. In contrast to the preceding revision, it supported two parallel CR2032 cells, of which only one was necessary to run the calculator.

Based on the same processor, a limited HP 12c 30th Anniversary Edition (NW258AA) was introduced in 2011.[14] Only 40,000 of this model were made.

The internal hardware of the HP-12C changed again in 2015, when the design switched to use an Atmel ATSAM4LC2CA-AU processor with ARM Cortex-M4 core.[2] The calculator's part number and physical appearance didn't change except for a "Rev 2" plate on the bottom side.[2] It continues to use two parallel CR2032 cells.[2] The firmware reports a 2015 build date.[2] Serial numbers starting with "PHA", "9CJ", "7CD", or "3CD" rule out the older model variant.[2] The 2×3-pin flash port now uses the USB protocol instead of a TTL serial protocol;[2] in addition to this, the calculator's circuit board features an unpopulated mount for a Micro-USB connector.[2]

The HP-12C is one of only four calculators permissible in the Chartered Financial Analyst exams, the others being its sister, the HP 12c Platinum, and the Texas Instruments BA II Plus and BA II Plus Professional.

Often referred to as a tool for "Old-ie Time-ies," critics of the HP-12C claim its early 1980s technology and style are antiquated. Proponents, however, are quick to note that the HP-12C continues to be both the de jure and de facto standard of high finance.[15]

HP 12c Platinum / Prestige

HP 12c Platinum
Type	Programmable Financial
Manufacturer	Hewlett-Packard
Introduced	2003
Cost	ca. USD 60,-
Calculator
Entry mode	Classical RPN (4 stack level), Algebraic
Display type	LCD seven-segment display
Display size	10 digits
CPU
Processor	6502 core (SPLB20D2[1] / 6502 core (GPLB31A[1])
Programming
Programming language(s)	keystroke programmable (fully merged)
Memory register	original 12c Platinum model: 7…20 (R0…R9/CF0…CF9, R.0…R.9/CF10…CF19) + 5 (n, i, PV, PMT, FV) + 11 (CF20,CF21…CF30) + 5 (X, Y, Z, T, LAST X);[16] later 12c Platinum variants: 7…20 (R0…R9/CF0…CF9, R.0…R.9/CF10…CF19) + 5 (n, i, PV, PMT, FV) + 61 (CF20,CF21…CF80) + 5 (X, Y, Z, T, LAST X)
Program steps	8…400
Other
Power supply	3 V (1x or 2x CR2032) depending on model

The HP 12c Platinum is similar in appearance and functionality to the 12C, and is designed to mimic the 12C whilst extending its capabilities in various aspects. The calculator was introduced in 2003, is visibly distinguished by its silver-colored upper half as opposed to the gold-colored plate on the original 12c. There are five variants of the HP 12c Platinum (including two special issues).

The 12c Platinum has a faster processor (originally a Sunplus SPLB20D2[1][17] with 6502 core), larger memory (for up to 30 CFj registers[16] and 400 program steps) and more built-in functions. It allows input to be entered in algebraic mode as well as in 4-level classical RPN. The calculator's particular implementation of RPN exhibits an unusual behaviour of the CHS key different from that of the 12C and other classical RPN calculators.[18]

The first HP 12c Platinum version (F2231A) did not have parentheses, which often led to awkward key sequences to solve problems in algebraic mode. Since 2005, newer versions (F2232A) of the HP 12c Platinum have parentheses on the blue-shifted functions of the STO and RCL keys. They also support undo and backspace and provide memory for up to 80 CFj registers. The firmware changes increased the ROM size beyond the capabilities of the original processor, so it was replaced by the Generalplus GPLB31A (still with 6502 core),[1] which is also faster.[19] It was manufactured by Kinpo Electronics.

In 2006, Hewlett Packard released a limited edition of the 12c Platinum to commemorate the 25th anniversary of the original 12C's introduction. The HP 12c Platinum 25th Anniversary Edition also has the parentheses feature and features the GPLB31A processor as well.

The latest revision of the 12c Platinum was introduced in 2007 (F2231AA).[20] As in the later revisions of the 12C, it features two parallel rather than only one CR2032 cells, but it continues to be based on the GPLB31A processor.

In 2008, the HP 12c Prestige (F2233A)[21] was released. It features a gold-colored plate like the original 12C, but is otherwise like the fourth HP 12c Platinum model (F2231AA).