hp65 vs 41c vs 35s µbenchmark

[Marcus von Cube]

(05-31-2014 09:52 PM)GeorgeOfTheJungle Wrote:  

(05-31-2014 08:25 PM)Marcus von Cube Wrote:  Don't get me wrong. In many aspects, the unmodified 30b is the faster machine. ...

...
But this µbenchmark isn't any faster in the 30b... Do you have any idea why?

It's probably just too simple. The 30b uses an HP legacy C library for all computations with a precision (and accuracy) of 12 BCD digits while the 34S is based on the decNumber library which supports arbitrary precision BCD numbers. Internal computations are carried out with 39 digits at least, some modulo calculations with a few hundreds of digits to avoid cancellation. More elaborate algorithms are coded as double precision (34 digits) keystroke programs to save flash space for the cost of execution speed (and the loss of a few digits of accuracy in double precision mode). The register formats are (variants of) decimal64 and decimal128 which need to be converted back and forth from/to the decNumber format. This is a lot of overhead and doesn't come for free in terms of execution speed.