Past HP quality and 41 emulators (long)



After having moved some boxes from one room to another, I put hands on a few of my HP calcs that were sleeping for years (without batteries of course). I immediately tried to power up a mint 41CV bought in 1985 : Perfect ! everything works... Same test on a very used 41C : OK ! Every key works, the card reader is alive... Wow, that's what I call quality. The 41CV didn't run since 1987 ! I remember having dismantled the 41C several times in 1988, then I never used it again. I'm amazed. Not to mention the LED calcs I successfully waked up ! All that funny stuff lives again since the last week.

Well, I wouldn't expose these beauties to any hazard by using them outdoors, so I'll keep running Warren Furlow's eV41 emulator on my iPAQ 1930 ;-) and play with the real calcs at home of course !

The 41 emulators are great, but IMHO they have a drawback which takes its roots in the 41's ROM code : if one tries to speed up the emulation to take advantage of nowadays' fast CPUs, guess what ? Every function key is immediately NULLed. Not very convenient. So, I wish I have some time to modify the code in order to suppress the NULL feature. Does anyone ever tried that ? Warren, what do you think about that ?

I'll be happy to have news concerning that trick... And if no one did it, if I have time, I'll let you know !

Regards from France


Ok, slightly off-topic:

I once made a game (SpeedMiner) for the HP-48 which also features the nice 'NULL' option if you press and hold a key .
It even shows NULL, as reminiscence to the HP-41 ;-)




Hello Raymond,

Just to say that I never considered (and will never consider) that the NULL feature is harmful. It really IS a good thing for the beginner -just was I years ago ! But as an "experienced" user, wishing to see programs run faster, I think that a great add-on to the emulator would be a way to "null" the NULL -pardon the pun. Something like a new option in the "settings" menu ?




You can patch the code to increase the delay.

Check the following article:



Patching the code wouldn't help too much on today's (very, very fast) PCs because you will still get NULL. The only acceptable solution is to slow down the emulator to the speed of real HP-41 when the key is down ...


On my Emu41, the keydown time is emulated as a number of CPU cycles, and is independant on CPU speed (as a side effect, there is no way to get a NULL display). The only limitation is that CATalogs are no more readable at full speed, that's why I implemented an auto-speed feature to slow down CPU speed (close to original one) when display is updated.


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