Internal Port 0 Test – Selects the Internal
loopback connections for testing Port 0.
Internal Port 1 Test – Selects the Internal loopback
connections for testing Port 1.
Internal Port 2 Test – Selects the Internal loopback
connections for testing Port 2.
Internal Port 3 Test – Selects the Internal loopback
connections for testing Port 3.
External Port 0 Test – Selects the External loopback
connections for testing Port 0.
External Port 1 Test – Selects the External loopback
connections for testing Port 1.
External Port 2 Test – Selects the External loopback
connections for testing Port 2.
External Port 3 Test – Selects the External loopback
connections for testing Port 3.
