Not remotely an HP calculator, but...

[jebem]

I finally managed to acquire one of these exquisite Hoopson PS-12MS calculators (Thank you so much Gerson for all your help).

This model can be found in some shops in South America, namely in Brazil.
I guess it is kind of rare, though, as an Internet search returns close to zero information.

This specific model is a Chinese made machine (where else?), distributed by "Mercoriental Importação e Exportação Ltda".

At first look it seems that this model is a clone of the Casio fx-82ms.
But the Mike Sebastian's Calculator Forensics test reveals a different beast inside, so it doesn't seems to be a exact clone.

This calculator seems to be able to work with 16 BCD digits internally, as the test result was 8.999999998078897 after extracting the remaining internal digits, and this result is different from the Casio signatures.

A quick Internet search for 8.999999998078897 forensics shows just a few machines with the same signature:

• Corner Office ATC-139
• Durabrand 828 (SC-1376 version)
• Fred's Dual Power Scientific Calculator
• Walgreens ATC-139
  

References found here:
https://www.rskey.org/~mwsebastian/miscprj/models.htm
http://calculators.torensma.net/index.ph...detail&;
http://www.datamath.org/Related/Freds/TI-30XIIS.htm
http://www.hpmuseum.org/cgi-sys/cgiwrap/...ead=112928

Specifications:

• Two "AA" battery cells (3VDC)
• Two line display (text on top row, numeric on bottom)
• 10+2 digit numeric display
• 240 functions
• Made in China
  

Powering the calculator off will clear the display and the replay buffer, but the memory contents is preserved including the Ans register value.




Forensics test - extracting the remaining digits.




And of course my preferred activity: Dismantling the machine to see what's inside.
The back cover maintains the LCD display and the processor board in place.
Four small metal self taping screws need to be undone to remove it.




Mainboard PCB label: 82MS-9-2 13.06.14

After removing the back cover, the mainboard PCB and the LCD display are floating around.
Flexible flat cables interconnect the keyboard and display to the mainboard assembly.

The membrane keyboard is fixed using undone plastic rivets. Didn't try to dismantle it.
Reset key contacts on the left of the mainboard PCB assembly.



Back side of the mainboard and LCD display.