QMS CrownCopy User Manual page 21

4 Line up the notch on the new PROM with the notch on the
MR10 socket. Carefully insert the PROM's pins in the socket.
CAUTION: If the PROM is installed backwards, it will be
destroyed when the printer is turned on. Also, make sure all of the
PROM pins get inserted into the socket and that none of them get
bent underneath the PROM.