BCD calculators

[Claudio L.]

(11-04-2020 12:41 AM)neyuru Wrote:  Hello all, first post here. By the way they handle arithmetic, physical calculators can (maybe?) be classified in broadly three groups:

1. Hardware based BCD
2. Software based BCD* (emulation)
3. All binary arithmetic (converting only to decimal for display)
   

* although I'm not even sure if this is actually implemented, but is a possibility.

Having an ASIC is not something a manufacturer usually conveys in its marketing, but I do appreciate a chip specifically designed to handle math operations in the way *most* humans do math. Some calculator models are known to have a BCD compliant microprocessor. Information on HP models is the easiest to find. Some modern calculators are based on ARM (or similar) processors (which I think excludes them from BCD, as they are basically tiny, power efficient "32bit or 64bit computers"- as in PCs with processors with binary arithmetic). Although they might be fast on benchmarks, they lack the soul of a calculator: as a device specifically engineered to do math fast and with as little resources as possible.

For my tastes, a "real" calculator* should have hardware based BCD. What are your thoughts on this? Does anyone know of any source that gives information on calculators falling in one of these groups? (there is at least one page with information on processors used for models but you would have to then investigate this chip and even if you find information about it, non technical users like me would most likely won't find anything useful in layman's terms.)
* by real I mean a device that is specifically designed to handle and give us answers in the language we are most familiar with: decimal.

I would love to know if modern calculators are still being made with ASICs instead of the ever present 32-bit or 64-bit general purpose processors.

First I'd like to make a distinction between decimal math and BCD. BCD uses a particular encoding, you can do decimal math with other ways to encode the number, it's still decimal but not BCD. Libraries like decNumber, mpdecimal, etc. fall in this category: it's decimal but not exactly BCD.

All HP calculators based in the Saturn chip (HP28, 39g, 40g, 48s & 48g, 49g), have hardware decimal support (actual BCD). Newer ones running on emulated Saturn run emulated decimal (39gs, 40gs, 49g+, 48GII, 50g). The HP Prime uses binary for HOME, and decimal for the CAS on an ARM (so it doesn't really fit well on your classification).

Hardware based solutions are nowadays not flexible enough. Hardware is being commoditized, and software needs to be portable, so you can develop software once and just replace the hardware when it breaks. Any software designed for specific hardware is condemned to die with that hardware.