MOP is short for
Maintenance Operations Protocol. It's a
DEC proprietary communications
protocol used in many DEC systems for things like, well,
netbooting
workstations. The
VAXstations, in addition to many other
VAXen have the client side support for MOP built into their system
ROMs. Without this
built-in MOP client code, we wouldn't get very far in netbooting the machines. This is because MOP provides the means by which the
NetBSD/
vax bootloader is transferred to the VAX client. To boot a machine from the
network using MOP you need to have a MOP server in addition to your VAX's client implementation of MOP
taken from the
NetBSD/VAX netboot
HOWTO