SCUBA - Nitrox and Trimix for HP-41

[4ster]

(09-15-2016 10:12 PM)Dieter Wrote:  

(09-15-2016 12:53 AM)4ster Wrote:  CLRGX - You are correct. I had an issue running the program on the iphone 41C app that halted the program at the CLRGX instruction with a NONEXISTENT and assumed that it was because CLRGX was an extended memory function.

CLRGX is a function that is only available on the CX (like some others). It is not a part of the Standard Extended Functions as they are available in the X-Functions module. So for CLRGX you must have an CX. At least if Ángel did not make some kind of ROM that includes it. ;-)

(09-15-2016 12:53 AM)4ster Wrote:  After all these years I am still confused when CLA is needed and when its not.

Simple. CLA clears the alpha register. This is not required if you enter a new Alpha text because this text overwrites any previous Alpha content that may exist. For instance, the CLA in the current line 77, 90 and 99 is not required, because the "MOD=" etc. text that follows overwrites any other previous Alpha content.

CLA is required if you want to start with an empty Alpha register and the next Alpha function *appends* text. This e.g. is the case with ARCL. It *appends* the content of the specified data register to the current Alpha string. For instance "VALUE=" ARCL X produces "VALUE=3.14" if X is Pi. If you want a message that *starts* with the x-value you'd have to clear Alpha first. Otherwise ARCL X would append X to whatever happens to be in Alpha at that point. That's why the CLA in line 48 and 65 is required.

Dieter

I write programs like I work on cars... They seem to run better when I have parts left over after putting them back together. ;-)