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. 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. 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. The calculator's part number and physical appearance didn't change except for a "Rev 2" plate on the bottom side. It continues to use two parallel CR2032 cells. The firmware reports a 2015 build date. Serial numbers starting with "PHA", "9CJ", "7CD", or "3CD" rule out the older model variant. The 2×3-pin flash port now uses the USB protocol instead of a TTL serial protocol; in addition to this, the calculator's circuit board features an unpopulated mount for a Micro-USB connector. 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. HP 12c Platinum / Prestige 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 with 6502 core), larger memory (for up to 30 CFj registers and 400 program steps) and more built-in