ARRGGG HP 41 double x memory experts, help


After following Christoph Klugs adobe file to the letter (IMHO) I doubled up my x-memory module with two x-memory chips.

I installed it in the Full nut HP 41 cx and did a cat 4 and got 600. Yahoo! so I then filled it with programs to the 589 point, i.e. 21 registers left and catalog 4 gave back all the correct program headers and byte counts. I then downloaded back to main memory a bunch of programs which loaded correctly.

I then tried to execute a program and the screen froze. Removing the module allowed the program to run. Single stepping the program with the module in and out also correctly ran. The calc freezes up with the module in and using the R/S function only.

I then tried my half nut 41cx and got the same response.

I then tried my 41c with Quad memory, extended functions module and the new 2-X memory module and it WORKS PERFECTLY with the new module, loading, downloading and executing.

To summarize:

HP 41 CX halfnut with new 2-x Module installed uploads and downloads to the module correctly. Programs operate correctly in main memory using SST command but not R/S. Cat 4 = 600.

HP 41 CX fullnut displays the same symptoms. Cat 4 = 600

HP 41 C fullnut with new 2-x Module installed uploads and downloads to the module correctly. HP 41 C also has Quad memory module and extended functions module installed. Programs operate correctly in main memory using SST command and R/S. EMDIR = 600.

Does it look like I just created a 2-x Module for the HP C only?




Did you follow Winfried Maschke's hints when wiring the chips?

Pointer: His comment in the 'Triple module thread'




Unfortunately no,

I used the articles published in the PPC and the article at the museum by Christoph Klug.

After about 90 minutes of finicky soldering I managed to get the module assembled.

It works in the HP 41C with an x-functions module and quad memory chip perfectly allowing all programs to execute.

It works in the HP 41CX for uploading and downloading but will not allow any file to execute as long as it is installed. The programs do execute with SST with the module in place.


Edited: 5 Apr 2008, 2:50 p.m.

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