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It is not the first time I ask: Who may shed some light on the internals of the HP-41 Infrared Printer Module (aka Blinky)? I am still not able to run it in my simulator, as I have absolutely no idea about the HW and its interaction with the firmware.

Any hint appreciated.



I always suspected the IR module HW has some relation to the HPIL, mostly because of the HPIL printer functions subset. What always called my attention is the fact that once the IR module is plugged in, the HP41 needs a brief moment - less than a second - to wake up after [ON] key is pressed. And this happens all the time, as if an HPIL is plugged in and the loop is opened.

Have you compared the MCode of the IR functions with the equivalent HPIL printer functions, at least some of them? Chances are they share some structure.

Not an answer to what you asked, I know, but chances are it may lead to some find-outs.


Luiz (Brazil)

Edited: 20 Nov 2012, 11:26 a.m.

HPIL inside Blinky? No, there are other time consuming procedures too. In my simulator the IR module runs in a endless loop that was until today too big to analyse, at least for me. I guess there is a flag that flips to indicate all's powered up and ready to go. All I could do is guesswork and that is not my kind of emulating or simulating.

BTW, I now adopted Eric Smith's wording, my NutEm is not an emulator, it is only an interpreter of the firmware written for the Nut CPU, and as such a simulator only.


Well, this also helps correcting my assumptions about the IR module.


Luiz (Brazil)

The Blinky hardware seems fairly complicated. I think there might even be a processor in there, but I'm not sure. I studied it a bit, but didn't really make heads or tails of it.

If I had a spare module, I'd consider decap and photomicrograph for reverse engineering, but I'm not going to do that with the one I normally use.

The only relation to HP-IL is that they deliberately implemented similar printer functions.

There are some code matches to the other printer ROMs, but all the low-level stuff is entirely different.

So my question to the expert: reverse engineering by analysing the firmare only is not possible? With my understanding it could be feasible (but I could be wrong), I just had not spent enough time on it yet.