Nintendo GAME BOY Programming Manual page 40

Game Boy Programming Manual
Receiver
1
Sender transmits connecting pulse.
2
The receiver calculates the width of the received connecting pulse. If the value is
correct, the receiver returns the same connecting pulse to the sender.
3
The sender calculates the width of the connecting pulse returned by the receiver. If the
value is correct, the sender determines that a connection has been properly
established.
4
The header is transmitted.
5
The data is transmitted.
6
The checksum is transmitted.
7
The receiver returns the communication status to the sender.
8
When communication is complete, the header of the subsequently transmitted packet is
set to 00h + 00h.
2.6.3.7 Details of Data Transmission and Reception
Connector
Light emission
Sender
Light detection
Light emission
Receiver
Light detection
The two Game Boy Color machines perform initial data reception, then the one designated
as the sender (e.g., by operations such as pressing button A) begins transmission.
Connector
(Indicates reading of the RP register)
40
Communication status