HP-32E Power supply -> HP-37E

[PANAMATIK]

(02-12-2021 10:26 PM)ytterligare Wrote:  I recently repaired a 32E, and saw that on the PCB the layout for a second switch was in place and unused...maybe it is the CPU that decide whether it is being used or not...

Indeed the firmware decides whether it is being used or not... , it tests the status bit 4 as the slider position. If you analyze the HP-32E firmware you will find, that this status bit is never been tested. Therefore changing the RAM ROM Chips will transform a HP-32E into a HP-37E, you even don't need to change the CPU.

The three RAM ROM chips can be placed randomly, only the C models need to place the RAM chip in the upper location, because battery plus powers only this chip when the calculator is switched off.

Bernhard