HP-41C service module question

[Jurgen Keller]

I use SM-1C aka ET-11966, the one described in the HP-41C Service Manual. There I also found the reference to ET-11967, see table 4-1. It's required to run the I/O Port test routine, see table 4-2, step 12. As in my opinion this is a very useful test, that's why I'm looking for information about this additional module.

I just checked the HP-41C/CV/CX Service Manual, and interestingly it does not mention this flag-wired module anymore. Instead it references an ET-11945 Port Extender for I/O port testing, see table 4-1 "Recommended Tools" and table 4-2, step 13 (I/O Port Test). Of course it would also be interesting to know more about this "beast".