Investigation needed on the 4-Player Adapter

[avivace]

There are a couple of statements that need confirmation in the DMG-07 article.

In the trasmission phase:

Then the master Game Boy (Player 1) is ready, it should send 4 bytes
(0xAA 0xAA 0xAA 0xAA, if those are actually required should be investigated further).
This alerts the DMG-07 to start the transmission phase.

Same in the "Restarting Ping Phase"

It's possible to restart the ping phase while operating in the transmission
phase. To do so, the master Game Boy should send 4 or more bytes
(0xFF 0xFF 0xFF 0xFF, it's possible fewer 0xFF bytes need to be sent,
but this has not been extensively investigated yet)