Digital Equipment DECwriter 500i Service Manual page 35

B INSTALL CARTRIDGE + D
Keeping these two keys pressed at machine power on, the
printer configuration parameters set in the factory will be
restored (default parameters).
B INSTALL CARTRIDGE + G PAPER MICRO-ADVANCE
Pressing these two keys simultaneously regardless of the
printer status, a machine reset is carried out (any printing
operation in progress is canceled and the data in the buffer is
lost).
PAPER DEVICE/ PRINT QUALITY
Functional Description 2-17