Speed comparison Swissmicros / HP

[Druzyek]

I just found this forum (woohoo!) and looking at all the threads from the beginning noticed this (I hope it isn't impolite to resurrect a dead thread here):

Quote:So, DM-41L running at 48MHz on LPC1115 (32-bit ARM RISC CPU) runs just slightly faster (73.7 vs. 87.6 sec) than the original HP-41CV while 15+ years ago I was able to emulate HP-41C/CV/CX which runs ~3x (HP-41X) and ~1.8x (HP-41E) faster than the original, all this on an ancient HP-48GX (4-bit "stone age" CPU at ~3.8MHz)!

The Saturn processor that the HP-48 models used seems to support BCD calculations natively. From Wikipedia, concerning data registers:

Quote:The 64 bits (16 nibbles) can hold BCD-formatted coded floating point numbers composed of a Plus and minus signs nibble, 12 mantissa digits and a 3-digit exponent stored in BCD format (±499).

I'm not sure how many cycles an add takes on the Saturn architecture, for example, but it is probably still many times faster than the equivalent calculation on an ARM, since BCD support is not built in and probably takes many cycles to perform in software. I have always suspected that this is why the HP-49G+ only got a "3-7x" speedup despite having a 75mhz ARM processor. Can any DM-41L experts confirm how the math library handles elementary BCD operations?