Total Repair

[PANAMATIK]

(06-25-2017 11:09 AM)PANAMATIK Wrote:  Success! After some more work this weekend to adapt the display scan and keyboard scan routines and the slide switch, I just got the HP-25E firmware with all its features running on this calculator.

The Total Repair is complete!

I'm quoting myself, because this statement was not really true. The repair couldn't be called complete at all. I had a lot of work ahead, not knowing how much, when I wrote the above lines. The hardware possibilities revealed an amazing new calculator.

Definitely this totally repaired and converted to an "HP-25 LP" calculator (LP for Low Power) will become my favouite LED calculator. It has fantastic new features.

1.) Power consumption is between 2-19 mA when display is on and 0.2 mA when in sleep mode (10000 hours with 2000mAh AA batteries).
2.) It has full alphanumeric capabilities.
3.) It can print on the HP82240B printer like the normal HP-25E
4.) I added the Real Time Clock chip, it provides accurate time, date and alarm time. Time, date or alarm time entry is very easy with the keyboard, just enter 6 digits and ENTER.
5.) The stopwatch can count upwards, downwards and you can enter values via keyboard. It is controlled by the RTC and hence very accurate.
6.) I added an alarm buzzer. The sound it very clear and you can use the HP-25 to wake you up every morning, the first ever red LED calculator with sound.
7.) I added the first ever alphanumeric program display of a red LED calculator. This changes the calculator completely. You can read your program steps. It works within PRGM mode and when SST BST R/S are hold down in RUN mode.
8.) All features of the HP-25E including 100 user programs, 100 constants, 88 registers can be stored in flash memory
9.) I made also a version "HP-29C LP" (Low Power).



The RTC (Real Time Clock) chip mounted and piezo buzzer attached, to be seen on these images of the prototype.



"HP-25 E LP" shows the actual time and date, like the HP-01 watch, but in time display it cannot display the semicolon.



"HP-25 LP" shows program steps in plain text, followed by a number or the key code. This is just an example. I never will miss this display in the future.

I also like to mention, that the ON/OFF switch is not longer connected. You can see in the images that it is in OFF position. The calculator is always ON and enters sleep mode when not used for some minutes or with f + division key sequence (like the pioneer LCD calculators, using the lower left button).

I will think about a way from the prototype to a small circuit board for everyone.

Bernhard