Check this guy out!

[agarza]

(10-29-2024 02:46 PM)Commie Wrote:  

(10-29-2024 02:02 PM)agarza Wrote:  Check out this post: DIY CALCULATOR

This calculator uses an ATMEGA328 microcontroller with 64-bit (IEEE 754) precision.

It’s not programmable, but it does have a standard TVM (Time Value of Money) and scientific functions.

Yep, nice design but the ieee 754 64bit floats are utilised and as pointed out already, ieee 754 binary floats are crap, one reason is passing input numbers through strings and back again to the display, when converting from strings to float(and back again) causes a small conversion error which grows as you pass back and move the floats around. The best is bcd floats because they are transparent to i/o or strings and here is the problem, all the compilers, that I have seen or made aware of either use ieee 754 32 or 64 bit binary floats. This is done intentionally to stop would be good calculator design and protects the lower end of the existing scientific calculator market. So the only option open is to go assembler and try and mix the software with a standard high level compiler, avoiding the ieee 754 floats. A big help would be to have access with 64 bit integer data type support but the one compiler (that I have seen) that supports this, costs about $1500.

Cheers
Darren

Your best bet would be to write your own 64-bit BCD library.