where am I wrong?

[Dieter]

(12-10-2016 07:20 PM)aurelio Wrote:  I cannot key 12345, always I get "TRY AGAIN",

PACKING and then TRY AGAIN tell you that there is not enough memory left to add the command you are trying to insert. But this should not happen here:

(12-10-2016 07:20 PM)aurelio Wrote:  that happens of course if following the previosus steps:
1.insert one memory module into the HP41C
2.execute a master clear
3.set SIZE 063
4.switch to PRGM mode

First of all, I assume you have a 41C (not CV, not CX) and you know how to do a master clear.

One single density memory module has 64 registers, plus 63 from the calculator itself makes 127 total registers. After SIZE 063 this leaves 64 registers for programs. This is what you should see after you enter program mode: 00 REG 64.

Now, what do *you* see here? Switch to PRGM and type [GTO] [.] [.], see 00 REG nnn. What is nnn in your case? If it's 00 the memory module does not work. For a test, set SIZE 017. Do you now see 00 REG 46? Then it's definitely the memory module.

Dieter