Posts: 301
Threads: 28
Joined: Jan 2005
If I recall correctly, you can replace the battery and the internal capacitors will preserve the memory content for a good time (some minutes, I think) without the battery. Please correct me if I'm wrong.
Best regards,
Nelson
Posts: 1,841
Threads: 54
Joined: Jul 2005
There's a capacitor inside the HP-41
which will protect memory for a
short time while changing batteries.
Since batteries can be changed within a few seconds,
normally no data will be lost.
However, this also is kinda RTFM;-)
AFAIK only the clock of the timer module
or the CX will have to be re-set.
Some of my HP-41s hold memory contents
for a few hours w/o batteries,
but that's not guarateed, of course.
It's always a good thing to have a
data backup on an external medium.
The card reader and the tape drive can be used
to store programs and other data.
You can even do a full backup of your HP-41
to cards or tape.
Raymond
Posts: 1,788
Threads: 36
Joined: Aug 2007
I have a couple of 41CX machines that hold for over a month without batteries. More typical is about a week... as long as you dont press any keys or try to turn them on.
Posts: 887
Threads: 9
Joined: Jul 2007
In almost 20 years of using my 41cx regularly, I have never had a memory loss except from a synthetic-programming mistake. The clock and alarms have not been affected by removing the batteries for replacement either.
The first CMOS computer I made, back in 1986, was breadboarded and had a 10uF capacitor from Vcc to ground. After the first day of experimenting with it all working, I shut it down, and was surprised to find the next day that all the RAM data was still intact, held only by the 10uF capacitor. I had not made a backup circuit for it yet to keep the memory alive on battery power while the computer was off.