A peculiar Casio fx-4000p

[jhlee0218]

Hi All,

A long time lurker here (for about 18 years I think). Recently, I started expanding my collection to some old Casio and Sharp models.

While playing with one of the recent acquisitions, Casio fx-4000p, I discovered something quite peculiar.

While it is supposed to have 550 programming steps (from various online sources as well as pg. 22 of the manual), I noticed that mine was showing 874.

I was further shocked when I checked the current memory allocation (by typing Mode -> . -> EXE). It says M-117 S-1874 which seems to suggest that it has 1874 (not 874) programming steps. Since the calculator can only display 3 digits of programming steps in the WRT mode (Mode -> 2), the first digit was hidden, thus only showing the last 3 digits i.e. 874.

I have not tested if I am actually able to use up 1874 programming steps (but the programming works as expected).

Any idea what is going on here? I opened up the calculator to clean the contacts and re-apply some double sided tapes, but did not observe any signs of modification.

Cheers,
J. Lee

[grsbanks]

That's a common form of memory corruption that arises when fresh batteries are installed.

Hit the reset on the back of the calculator and things will return to normal.

[Dave Britten]

Yeah, VERY typical with most Casio calculators/pocket computers up through around the mid '90s. They don't detect the invalid RAM contents when you first install fresh batteries, and you have to hit the Reset button, or else you'll see all sorts of weird behavior (such as bogus free memory counts).

[jhlee0218]

Thank you for the replies! Indeed, resetting the calculator has brought the number of programming steps back to 550. I was excited for a few days thinking I obtained a silently upgraded fx-4000p...