CASIO fx-3900P memory increasing (with keystrokes) is possible?

[Csaba Tizedes]

I found this pdf: Calculator programmes (Mr. Francis Hung) with the following interesting last page:

To increase the number of steps of memories in 3900p
(1) Open the case with screw driver
(2) Take out the batteries
(3) Close the case with screw driver without batteries
(4) Press several times “AC”
(5) Open the case with screw driver and then put the batteries into the case
(6) Close the case with screw driver
(7) Turn “on” the calculator and press ‘mode’ + ‘0’
(8) Clear programme 3 and programme 4
(9) In programme 3, enter 150 ‘+’, in programme 4, enter 151 ‘+’
(10) Clear programme 1 and programme 2
(11) If the number of free steps + number of steps in programme 3 and programme 4 > 1200 steps, then the modification of calculator is completed, otherwise, it has to be started over again.
(12) Press ‘Mode’+‘.’, ‘Mode’+‘4’, ‘Mode’+‘9’, ‘Shift’ + ‘AC’, ‘Shift’ + ‘MR’.


Any experience about this method on this or on another calculator?!
Any similar trick for other models (I can imagine my fx-50F with 1200 bytes memory)?

Thanks for any reply!
Csaba