Dorio 20 is a VT520 compatible.
Ports Dorio 20
Comms 1 DB25 RS232 Female
Comms 2 DB25 RS232 Female
Comms 3 DB9 RS232 Male
Printer port is DB25 RS232 Male.
Ports on VT620
Comms 1 DB25 RS232 Female and alternatively DB25 RS232 Male
Comms 2 MMJ DEC 423 Female.
Comms 3 MMJ DEC 423 Female.
Printer port is DB25 RS232 Female.