I have received a couple of questions about the HP 12 C variants. As you all know the HP 12 C is the longest existing product in HP range. It was one of the original Calculator in the Voyager range, and it started to sell in 1981. Hence the 30th anniversary title of the latest version.
The original versions were produced with the technology of the day. They were based on a Coconut-type processor, but running at an even lower speed than the HP 41C, that is 250,000 kHz instead of 640,000 KHz in the Hp 41c. It shared exactly the same processor as the rest of the Voyager range, the only difference between them were the ROMs that each one was using. All Voyager calculators did use a 4 kbyte ROM, except the 15c which used 8 kbytes. When you compare that with the current operating system sizes, several million times bigger, it is amazing how much Mr. Kahan and the HP engineers were able to put in so little silicon space.
The latest versions are based on an ARM processor, running an emulator of the original processor, with a much higher clock speed. This speed can be changed according to the state of the calculator: very low when waiting for a key press, extremely fast when running a program. This is used to lower energy consumption when it is not needed, and be fast when required. And it is fast! My estimate of its relative speed compared with the original, is of about 150 times. Even the newer version of the HP15c does not fare as well as the 12c, at around 100x. And all this, running on an emulator layer!!!
HP discovered that some users did not accept a very fast 12c. They expected it to take its time when solving for interest, distrusting it when the results appeared too fast.
Still, this is a calculator that all users covet - and that they try to replace whith a new one, when -and if- it dies or it is stolen.