The HP designjet 650C PS is an amazing printing machine manufactured by HP, the United States' firm which has established itself as a reputed technology giant. The device comes with model numbers C3791A (D/ A1 size) and C3792A (E/ A0 size). The device also has 4 MB of standard RAM installed. It is also equipped with Postscript ROM SIMM along with a Jetdirect MIO card. The two HP designjet 650C PS models require at least 4 MB of RAM in addition to the onboard RAM. It has centronics interface too.