Custom Menus on High-End RPL Machines

[Raymond Del Tondo]

(04-02-2019 03:58 AM)Thomas Okken Wrote:  

(04-02-2019 02:07 AM)Giuseppe Donnini Wrote:  Well, for pretty much everything! It may be hard to believe at first, but to quote the most knowledgeable person I know of on that subject:

That's tantalizingly vague.

So if I were to try to disassemble the 42S ROM, I would find the floating-point routines in machine language, I guess, and perhaps the complex and matrix functionality as well, and the graphics primitives? With the command line interface, menu system, program editor, and program interpreter in (compiled?) RPL? Am I warm? Has anyone delved into this and written any articles about it?

Yes and no.
Many years ago, I disassembled (and partly decompiled) a huge amount of the 42S ROM.
The RPL kernel is nearly the same as in the HP 48S series, lacking things like bank switching and some object types - things which are not used in the 42S.

There are similar (if not the same) math routines in ML, and math related routines in SysRPL. The latter are nearly the same as in the HP 48S series.
The user interface is different to that in the HP 48, so the associated display graphics routines and menu display routines are different, of course.

The stack registers incl. Alpha are stored in designated positions in system RAM, the registers are incarnated as a matrix object.

There is no User level RPL in the 42S, only SysRPL. So if you are in the 42S program editor, you'll only have access to FOCAL words, with some 42S extensions, of course.
The program "compiler" creates a FOCAL byte stream, which will be run through the FOCAL execution engine.
This FOCAL byte stream is binary compatible to that of the HP-41 and the HP41CV Emulator card for the HP 48SX.

The actual internal code behind the FOCAL words is RPL or Saturn ML, of course.