Garbage in HP50g ERAM when battery low

[Erik P]

When the batteries (NiMH) in my hp50g are getting old the ERAM sometimes gets completely filled with garbage. Often I can remove - purge - some, but far from all, of the entries in the ERAM. There is always some entries left that I can not remove, and no matter how many entries I remove, the calculator reports the free memory of the ERAM as 0. The only way I found so far to recover the ERAM is to do a full reset. This is however a bit annoying since I loose all settings.

Anyone else who has this problem?

Anyone who knows a solution, at least to the problem of removing the entries? Is there a way to reset just the ERAM?

[John Keith]

I haven't had the ERAM problem but I did once have the calculator crash with garbage in the display when using NiMH batteries. I think the problem is that NiMH cells can lose voltage suddenly when they get low and the calculator's circuitry can't handle it. I just stopped using NiMH and went back to alkaline cells.

[rprosperi]

(05-25-2019 10:47 PM)Erik P Wrote:  When the batteries (NiMH) in my hp50g are getting old the ERAM sometimes gets completely filled with garbage. Often I can remove - purge - some, but far from all, of the entries in the ERAM. There is always some entries left that I can not remove, and no matter how many entries I remove, the calculator reports the free memory of the ERAM as 0. The only way I found so far to recover the ERAM is to do a full reset. This is however a bit annoying since I loose all settings.

Why not backup your settings (and other objects) to Port-2(Flash) or Port-3(SD card) before you reset the device, then you can restore them? Note though, it has been so long since I manually did a reset, I'm not sure if Port-2(Flash) is wiped. In any case, removing the SD card will keep that safe during the reset.

[Erik P]

(05-26-2019 01:30 AM)rprosperi Wrote:  Why not backup your settings (and other objects) to Port-2(Flash) or Port-3(SD card) before you reset the device, then you can restore them? Note though, it has been so long since I manually did a reset, I'm not sure if Port-2(Flash) is wiped. In any case, removing the SD card will keep that safe during the reset.

Thank you! I do save my objects in flash-memory and if I choose "Recover memory" no objects have been lost so far (I haven't done it enough times to say anything more general). It is however a bit annoying that this is necessary. The settings are however lost. If I understand correctly I can use RCLF and STOF to retrieve and store the flags, and use STO etc to save and recall them as an object, which I include in the backup saved to flash. However, out of curiosity, does this include all settings, such as the font settings? I haven't seen the font settings among the flags and it is not a "flag" type thing (ie a flag has exactly two states).

[ijabbott]

Perhaps it is time to replace the CR2032 backup battery?

[TravisE]

I don't think font settings are stored in system flags (installation of custom fonts definitely is not, at least). You will have to save this separately, or arrange to have the desired font reinstalled after the system is restarted. Creating a program named STARTUP in the HOME directory is a good place for this, as well as restoring other desired settings; this program will be executed automatically upon each warm restart.

ijabbott has a good point: It might be worth trying a new backup battery. Extensive corruption of Port 1 seems like an odd symptom even considering a sudden power loss. I've never encountered that myself. I use NiMH AAA batteries but always replace them before or as soon as the low battery indicator appears. I don't take chances with letting them run out completely. (Even on the rare occasions when they have run out completely I have not seen this behavior.)