hidden directory - hp 28s

[Raymond Del Tondo]

(06-07-2015 04:30 PM)Dave Britten Wrote:  [..]
This all leads to another interesting question: What would it take to port the 42S user environment to the 48?

That was my main intention back then:-)
It can be made, but as always there are some obstacles to overcome.
The RPN stack and other stuff is stored in reserved locations in system RAM. This may have to be adapted to a LAM or similar. Unfortunately LAM binding also exist in the 42S, therefore I mentioned "similar".
Other things are the display and menu structure, which have to be adapted, which will be much work.

My over-the-thumb-calculation back then came to the result that the final 42S application on the HP 48 may have a similar size as the original ROM in the 42S itself, about 64K, maybe somewhat less.


After all, I took the other route, and reworked the existing HP-41CV emulator by Frank Wales.
Very much work, too, but the main pain was to make the code relocatable. The original 41CV Emulator makes heavy use of absolute jumps, which helps to gain space and speed. There are many jump tables and tricks to squeeze the code into the 32K limit of the ROM card.

My version is about 41K in size, can be stored in any port at any location.
The whole thing now resides in a single library.

Since reworking the direct jumps to relocatable jumps lead to more code to run for jumping to a destination, the wole code ran somewhat slower on a GX than the original code on an SX, so especially the display routines had to be heavily optimized for my version.
Now the stack display in my version is about as fast on a GX as the original version on an SX.

(With "now" I meant the year 2003)

Since my relocatable GX version of the Emu41CV runs stable since year 2003,
maybe it's time restart the initial idea of a 42S application again;-)

However the upcoming new SpeedUI version with support for 32K 48G units has priority, so maybe this fall or winter could be a good starting point for a project like this.
One question is: Are there more than 2 or 3 people who would like to have a 42S simulation on an HP 48?