Extended IO ROM incompatible with 1F IL module ROM

[born2laser]

I figured it out!

Turns out I was unjustly blaming the CL or the ROM image (I will rename the thread after I post this). I was forgetting the other difference in my tests. For the V41 I was using a virtual HP-IL module, with the CL I was using a real module. I did not test with my CV because I don't have (yet!) the possibility of loading ROM images, so I can only do it with the CL
My HP-IL module has a different version of the ROM (-MASS ST 1F) from the one in the virtual module (-MASS ST 1H). The Extended IO module makes a direct call to the HP-IL module at address 73F8, in the 1H version there is a little loop that reads data from the drive at that address, in the 1F version this lands in a pocket of 18 NOPs, most likely reserved space for future development (duh!). I am attaching the ROM images for those interested.
Now, I already knew my HP-IL module was primitive, but since I had not noticed any difference up this point I had completely forgotten about it. As you can see in the linked photo my module is actually a "PIL Module". I got a good deal in TAS because I purchased "as is, untested".
I believe the name of the loop changed at some point, besides my module I have what appears to be an internal HP document (from 1980, downloaded from the *** site) that contains basically the same information as the 82166 document (from 1982) available in Eric's site, but refers to the loop as "PIL"

Anybody knows the history and wants to share it?
Also, for the collectors out there, have you seen a module like mine? How rare is it?

Juan