Extending the precision of Woodstock or Saturn based calculators

[J-F Garnier]

(08-10-2017 05:58 AM)Alejandro Paz(Germany) Wrote:  

Quote:I suspect it would be better to produce new algorithm for the higher precision. Nobody is going to make an advanced NUT processor when there are a plethora of adequate processors available already.

I am trying to develop such a processor, a better Saturn if you want. FPGAs are very flexible !
I have other algorithms for ARM/MIPS processors.

Several years ago, I made similar investigations. Not really to get higher precision, but to provide higher speed and/or higher memory capacity.

For the HP41, I considered (in my Emu41) to implement a floating-point unit (using a unused Nut opcode), with the goal to simply re-write the system math routines. I ever made it (and will no more try) but some traces of my thoughts can still be found in my Emu41 sources (nutcpu.c).

For the HP71, I once considered to increase the width or the A address field from 5 to 6 nibbles, to increase the memory space. But the compatibility problems with the existing firmware were too important, and I gave up.
I also considered a FPU extension.
All I did in my Saturn emulation was (as you know) to add the R5-R7 registers (allowed by the opcode map) and increase the stack depth, although the HP71 firmware was not changed to take benefit of it.

Fell free to re-use these ideas!

J-F