HP41.org

Posted: **Fri Oct 16, 2009 9:51 pm**

Ok, I'll admit I'm a long-time TI user who just got hold of a 41cx emulator. I LIKE the 41cx... but...

I load a module, let's say the "CIRCUIT" module. I then place the keyboard overlay on.

The key that used to be "summation minus" now has a blue R underneath it. I know that this is for Resistance. But when I push that key, it still acts like "summation minus".

The question, when a module is loaded, how does the 41cx know to change the keys to the new assigments? You can load four modules, so I assume it doesn't load them all for the same keys.

Thanks. - Roger

Posted: **Sat Oct 17, 2009 2:35 am**

There are several ways it can be handled, but the most common, and what is probably used by your module, is probably the local alpha labels (A through E, a through e, and F through J) and USER keyboard. From page 300 of the 41cx manual:

Local Alpha Labels. Local Alpha labels require two bytes of program memory and can be used for branching any distance within a program. They are designed for manual execution: when the User keyboard is active, a local Alpha label is automatically assigned to each key on the top two rows (as described in "The Top Two Rows" in section 9). You can then use these keys to execute the corresponding local Alpha labels in the current program.

Program Example. The program <sigma> [I don't know how to put the Greek character here] in section 22 displays CLEAR D, J? E, which is a menu offering three alternatives. You can press D to clear days, press J to clear a job, or press E to exit. When you press one of these keys, program execution starts at the corresponding local Alpha label.

Page 169 however says that if you have something else assigned to the key, your own assignment gets priority over the program's local alpha labels' assignments.

Another way I have used a lot is GETKEY, GTO IND X with numeric labels so I'm not limited to the top two rows. I make any error condition just put you back to the GETKEY line to try again. Less-suitable methods would be to read a key-assignments file on mass storage with READK, or have the program re-assign the keys with PASN.

Posted: **Sat Oct 17, 2009 1:46 pm**

I agree Garth. The overlay does appear to rename those keys, but the actual key appears to ork the same as if there were no overlay.

Do I activate the keys by calling up a program from the module that willl rename the keys only while it is active? Thanks

Posted: **Sat Oct 17, 2009 4:18 pm**

Yes. Local alpha labels are only active while you're in that program. If you go to another program that uses them, those keys' functions will change accordingly. The computer has no idea what overlay is on there or whether there's one is even on it.

Posted: **Mon Oct 19, 2009 6:38 am**

Try to activate the "USER" keyboard by pressing the button right to "ON". This should activate the user mode, where some keys are redefined as indicated by the overlay. Then press an hold the button, depending on your emulator/simulator, the display should show what the keypress will do. If you hold long enough, the keystroke will be canceled.

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REALLY dumb question about overlays

REALLY dumb question about overlays

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Re: REALLY dumb question about overlays

Re: REALLY dumb question about overlays