The bizarre Casio FX-840P

[Jeff_Birt]

(06-22-2022 10:14 PM)BruceH Wrote:  If the calc doesn't bother to check for more RAM at power-up, why would there be memory allocated for RAM pointers? The values could just as easily be held in ROM.

It does check for the presence of the external RP-33, 32K RAM module. When installed it finds this and the amount of free RAM displayed is adjusted accordingly. It just does not seem to discover the additional 24K of RAM internally.

I played with it more last need PEEKing the values at $1000 intervals, increasing by 1, and POKEing back then PEEKing again to make sure the values changed. The FX-850P page on Wikipedia says it will reflect $0000-$1FFF to $A000-$BFFF, $C000-$DFFF, $E000-$FFFF without a full compliment of RAM, but I see no evidence of that on the FX-840P with the internal 32K and external 32K installed. I'll have to pull the RP-33 module and try the tests again.