External I/O (Smartstream, etc.).

[cyrille de brébisson]

Hello,

So, what you really want is a way to send/receive USB messages from the calculator, and you were thinking: if I make myself look like a data streamer, I might be on the right tack...

There are 3 roadblocks with what you are trying to achieve.
1: the Prime OS would need to recognize YOUR device VID/PID. The OS that we use does not do anything with USB devices that it does not know. Solving this is easy, you just need to hijack the VID/PID of either the Streamer, USB Dongle or other calculator. But then your device becomes indistinguishable from them.
2: Your device has to be HID. This is the only USB protocol supported
3: There is no user accessible functions to send/receive USB reports.

3 is a big blocker there as you (as a Prime user) have no ways to control that.

so, sorry, but would not work at this point in time.

Cyrille