Investigation needed on the 4-Player Adapter

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)