A HP 15CE keyboard handler bug?

[Martin Hepperle]

So far I was able to lock up my HP-15CE three times.
All cases seemed to be related to pressing "some" keys (in the heat of the battle, I could not reproduce the first instances when this happened).

However, I can reproduce the last case with my unit. Is this a general problem?

Key sequence:
1.) Hold 'f' and ENTER, press ON, release f and ENTER, then ON
=> The calculator switches ON and appears normal.

2.) Now try to switch if OFF by pressing the ON key
=> nothing happens. The ON/OFF key does nothing.

3.) Repeat the sequence (with the calculator still locked in ON mode):
Hold 'f' and ENTER, press ON, release f and ENTER, release ON
=> The calculator switches off.
After this sequence, the ON key seems to work normally as it should.

Also, pressing 'f' toggles the 'f' annunciator, but pressing it again does not toggle if back to unlit. Same for 'g'. Is this intended behavior?

The sequence can occur accidentally or when one tries the self test but confuses the 'f' and 'g' keys.
Initially, before discovering the 3.) workaround, I removed batteries or pressed the reset button for recovery, but this clears the memory.

Martin

[Maximilian Hohmann]

Hello!

I would say that this is a feature, not a bug: An "ON lock" that prevents you from accidentally switching off your calculator during the most critical phase of your lunar descent...

Regards
Max

[J-F Garnier]

Reproduced on the latest firmware 2023-11-06.
It doesn't happen on the previous firmware 2023-01-05.

Note that when in this locked ON state, the machine is in a high power consumption state, so don't stay in this state for too long.
I noticed that by removing one battery and monitoring the battery voltage that then drops from ~3.0V in idle state to ~2.6V in high power state.

A minor issue with easy workaround, but good to know it.

Quote:Also, pressing 'f' toggles the 'f' annunciator, but pressing it again does not toggle if back to unlit. Same for 'g'. Is this intended behavior?

This is the original 15C behavior, so I believe it's intended.

J-F

[brouhaha]

(02-02-2024 08:24 AM)Martin Hepperle Wrote:  Also, pressing 'f' toggles the 'f' annunciator, but pressing it again does not toggle if back to unlit. Same for 'g'. Is this intended behavior?

Yes. to cancel the f shift, press the backarrow key, whose f-shifted function is "clear prefix".

To cancel the g-shfit, press f and then backarrow.

HP established that mulltiple presses of the shift key don't toggle it at least as far back as the HP-80, in 1973. With calculators that didn't display the shift state(s), I suppose that made sense.

[Maximilian Hohmann]

Hello!

(02-02-2024 09:09 AM)brouhaha Wrote:  To cancel the g-shfit, press f and then backarrow.

Which is something that never made any sense at all. Since there can be only one active prefix at any time, only one Clear-Prefix function is required to clear it. Unless the developers had in mind to implement functions that needed f and g shift together.

Regards
Max

[Divasson]

Hi,

About this newly discovered mode:

- This happens only with the 100ms rebound The Calculator Store supplied firmware ("enhanced") with checksum C6C6h and dated 2023-11-06
- If you connect to a PC with the cable, you will see the calculator in usb as HPb10II+. This mode is intended to back up the calculator user memory - but we're still missing the PC side app.
- To go out of this mode without resetting, press f-ENTER and "on" again.

So, it is a feature, not a bug. To be updated shortly...

[Martin Hepperle]

(02-02-2024 09:46 AM)Divasson Wrote:  Hi,

About this newly discovered mode:

- This happens only with the 100ms rebound The Calculator Store supplied firmware ("enhanced") with checksum C6C6h and dated 2023-11-06
- If you connect to a PC with the cable, you will see the calculator in usb as HPb10II+. This mode is intended to back up the calculator user memory - but we're still missing the PC side app.
- To go out of this mode without resetting, press f-ENTER and "on" again.

So, it is a feature, not a bug. To be updated shortly...

I confirm, that this is one of "your" HP15CEs, flashed with the improved HP-16CE easter egg (unfortunately yet without the cable).

[brouhaha]

(02-02-2024 09:22 AM)Maximilian Hohmann Wrote:  

(02-02-2024 09:09 AM)brouhaha Wrote:  To cancel the g-shfit, press f and then backarrow.

Which is something that never made any sense at all. Since there can be only one active prefix at any time, only one Clear-Prefix function is required to clear it. Unless the developers had in mind to implement functions that needed f and g shift together.

No, they just didn't want to give up TWO possible key assignments to clear prefix. The key for clear prefix only does that for f shift. The g shift of that key is used for another function.