HP 41C Video interface test. Howto?

[tribidouille]

@vassilisprevelakis. Thanks a lot, very interesting. I'll search in this way when done with Sylvain Cote's tests.
@Sylvain Cote, Thanks also much.
These step tests are teachfull. #1 ok, #2 ok, loop works.
Effectively, the test #3 fails: Even with 82163 plugged and powered (before the 41), flags 21 and 55 show NO and I get a "Transmitt ERR".
I can deduce the failure is in the loop part of the 82163. One of its components for communication may fail.