Question about HP 41CX Memory Allocation

[Joe Horn]

EDIT: Oops, Les beat me to an answer. Oh well, I hope something in the following is useful. -jkh-

(09-06-2014 05:44 AM)EdFab Wrote:  I believe I have a fully functional HP 41CX but there is something I don't understand about memory allocation. I've been reading the online instruction manual for the HP 41C, and it says that the SIZE function will prompt for a 3-digit number between 000 & 318. Since the HP 41C comes with 63 registers, I'm assuming that the 318 limit only realistically applies if extended memory modules are installed. Please correct me if I'm wrong about this assumption.

No, extended memory modules do not expand regular memory, they only expand "extended memory" which is different from main memory. A useful analogy is to think of extended memory as a tiny built-in disk drive, which you can store stuff onto, and recall stuff from, but which doesn't increase your main RAM.

(09-06-2014 05:44 AM)EdFab Wrote:  After doing a memory clear on my HP 41CX, I did a shift->GTO .., and got "00 REG 219" in the display. I interpret this to mean that there are 100 data storage registers allocated, with 219 registers available for programming.

Yep.

(09-06-2014 05:44 AM)EdFab Wrote:  However, I have an X Memory module installed (I believe it's a double X Memory module at that, since CATALOG 4 gives me 600 in the display).

Yes, it's a dual X memory module.

(09-06-2014 05:44 AM)EdFab Wrote:  So my question is: Is it possible to allocate some of the registers on the X Memory module for data allocation? Could I enter SIZE 400 for example?

No.

(09-06-2014 05:44 AM)EdFab Wrote:  Incidentally, I get the display of 00 REG 219 whether the X Memory is installed or not. So how does the X Memory module come into play at all?

Read Section 13 (pages 204-227) in the 41 CX Owner's Manual, and Appendix E (pages 370-373) and the table of Extended Memory Functions (pages 425-428). Then you'll be an expert at using extended memory.