futile inquiry............


The very nice HP 41 repair manual refers in large part to a test module, and other special test gear which naturally is not available anywhere. Equally naturally, you need it to diagnose effectively and easily, unless maybe you have detailed design info of the calculator.

Since the module consisted apparently of a program rom and possibly other logic parts, it clearly could be made, given information. So could any other test fixture.

Has anyone ever come across information sufficient to construct and program these items? Or found one surplused out by HP (hah)?


I do not have the diagnostic ROM, but it does exist. A friend used to have acopy of the ROM image loaded in an EOPROM Box. The ROM uses the control code that is also used in the AUTOSTART/DUP ROM. That is it runs uimmediately when you turn the HP-41 on.


I use a W&W 32K RamBox with the Diag' Rom at page 4 (configure the switches then). It works fine! I have a "hand made" 4K Eprom Box which needs a couple of 2716 and 2732 Eproms. I think I have somewhere files in order to burn them.



ON 2
OFF 1 3 4 5 6 7 8

OFF 1 2 3 4 5 6 7 8

OFF 1 2 3 4 5 6 7 8

Turning on the calculator gives: CPU OK and later: SELECT CPU

Key "-" show the Rom version (for instance it's a 41CX): ROM 0:N 1:F 2:L





Actually the diagnostic module is not all that useful. If the system does not work at all the module will be useless. If it does, the ROMS are almost always good (if you have the card reader run the HP97 diagnostic program). The system does a quick RAM check when it turns on to size the system RAM. If you don't have what you're supposed to, a RAM chip is bad). Generally just exercising the machine will tell you all you need to know.

I test the keyboard by going into alpha mode and pressing each key three times. Erase the string when the buffer fills up and keep going.


the thing wouldn't be much help for a dead unit like mine.

But, for a unit that has an "issue" I can see it might improve diagnosis to the component or module level..

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