41CX Startup Program?


Is there a way in the 41 series (native or with a module) to have a program execute on start up?

The point would be the have the calculator always start up in a known state (e.g. flag settings).



Yep, native:

Automatic Execution Flag:

If flag 11 is set the HP-41C automatically begins executing the current program whenever the calculator is turned on.


Edited: 13 Oct 2009, 12:08 p.m.


Thanks. But, what I am looking for would be a default program. Is that possible?


That's one of the functions of the Autostart/Mass Duplication ROM. The microcode function to support that was also in the HP SDK for use in custom ROMs.


Hi Eric, guys;

when I first read about the AutoStart & Duplication ROM I felt intrigued by such feature. Anyway, some other ROM seem to take advantage over this feature, like the CCD ROM, AECROM and the FORTH ROM. By inspecting the FORTH ROM module listing, the last parameters after the main ROM space refer to such things as 'PAUSE interrupt' (#8FF4), action 'After each program line' (#8FF5) and so. All of them have a NOP code (that´s what we see in most ROM listings) except for the 'Awaken by pressing ON key' (#8FF9), which has a jump code for label 8FED (3A3: JNC -0C 8FED) in this FORTH ROM. Label 8FED is actually the last label in the listing and it seems to perform some sort of custom default setting. In fact, these three ROM modules actually reconfigure the HP41 standard keyboard in such a way the calculator performs custom tasks for regular keys when it is not in USER mode, and this should be done every time the calculator is turned ON (the calculator will never know if the module has been removed prior to be turned back on). I do not 'read' HP41 machine code without a table, so it would need further inspection. If the action to be performed when the calculators is 'Awaken by pressing ON key' can be defined by a user program, then we have a bunch of possibilities left...


Luiz (Brazil)

Edited: 13 Oct 2009, 1:37 p.m.


To complete my previous answer:

Upon turn on, the 41 will clear flag 11 before autoexecuting the program.

Therefore your autoexec program must set it again to ensure another autoexec at the next OFF/ON cycle.




Without using the modules, I have my sumation key (just under the ON key) assigned to a program that says SF 11, OFF. I never turn the 41 off by pressing ON, only by pressing the sumation key. The next instruction is where I want execution to pick up automatically every time I turn it on. That includes setting the constant-ON flag, then ENG 3, then seeing if an alarm is pending, and if so, display how long until it is due. Otherwise, it next checks to see if there's something in the DAYTIMR file it's supposed to remind me of, and if so, display that. Otherwise it goes on to display the time and date.

Edited: 13 Oct 2009, 5:24 p.m.


Great idea, very close to what I was looking for. Thanks.


Hi, guys!

This isn't what Egan was seeking, but there was a long-ago entry in the MoHPC Memories section describing the built-in capability mentioned by Etienne:


-- KS

Edited: 14 Oct 2009, 1:03 a.m.


The EXT-IL-PLUS Module includes the start feature of the AUTO-DUPLICATION ROM. Place a program in main memory called / named RECOVER, this is executed after switching ON HP41...

Best regards - Christoph Klug


Excellent, I will give it a try today. Thanks.



Just tested it. Absolutely perfect. Exactly what I was looking for. Thanks.


Dear Egan,

nice to hear that you like the autostart feature of the EXT-IL-PLUS module :-) I think this module is a nice collection of commands for advanced HP-41 applications...

Some more details about autostart and switching on HP-41 by an external wake up event you find in The IL2000 Interface System manual...

Best regards - Christoph Klug

Possibly Related Threads…
Thread Author Replies Views Last Post
  HP Prime: run a program in another program Davi Ribeiro de Oliveira 6 2,663 11-11-2013, 08:28 PM
Last Post: Davi Ribeiro de Oliveira
  HP-85 Display Error on startup hogelmann 3 1,322 11-19-2012, 10:57 PM
Last Post: Paul Berger (Canada)
  HP 41CX locked in program mode Steve Leibson 7 2,123 10-03-2009, 12:15 AM
Last Post: Randy
  Hp calculator (41CV/71B) startup question Kou Tadayoshi(United States) 6 1,963 05-06-2008, 04:39 PM
Last Post: Kou Tadayoshi(United States)
  HP-41 MCODE: Making an MCODE program call another MCODE program Geir Isene 10 2,808 01-13-2008, 05:58 AM
Last Post: Raymond Del Tondo
  Re: HP-41CX sun position program. Wilhelm Loidl 13 2,849 04-17-2006, 09:09 PM
Last Post: Ed Look
  i lost my program on my 41cx ross denys 9 2,230 12-11-2005, 03:25 AM
Last Post: Garth Wilson
  HP-41CX sun position program. Michel Beaulieu 10 2,377 12-02-2005, 12:31 PM
Last Post: Norris
  hp 41cx - Surveying COGO Program altanet 1 870 07-29-2005, 12:31 AM
Last Post: db (martinez, ca.)
  Startup script for 49G+ Tony 15 3,106 07-08-2005, 06:21 AM
Last Post: Tony

Forum Jump: