You are kindly asked to change the default settings to black&white print to avoid the involuntary abuse of colour prints.

from the bottom of this page download the correct version of the drivers
install the drivers
from the System Preferences select the Print & Scan and click on + to setup a printer
Click on IP, select HP JetDirect as the protocol and 4550ci.iom.cnr.it as the hostname
when the printer is recognised you can add it

To enable the grayscale printing, you are kindly asked to change the default settings and create an additional preset for the colour printing.

open an application from which you can print and open the print dialog
select the newly added printer and click on Show Details
select the Printer Features drop down and the Graphics 1 feature set
check that the Color mode is set to Full color and Save the current settings as Full color preset
open in a browser the URL http://localhost:631/printers
click on the added queue and select Set Default Options from the drop down menu
click on Graphics and set the Color Mode to Black & White
click on Set Default Options

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