17 May
2013
17 May
'13
6:38 p.m.
On May 17, 2013, at 11:34 AM, Bob Armstrong wrote:
John Wilson wrote:
this is a ridiculous security risk
so that's why MOP had a magic number
Yep, even the DMR has a boot "password", which is just an 8 bit value set
by dip switches on the board, that has to match up with the MOP message.
They DMA a small program into memory
Ah, I was wondering about that, because there aren't any separate boot
ROMs on the DEUNA. I bet the "small program" is just part of the T11 code.
And I'm assuming that this scheme didn't work on any UNIBUS VAXes - only
PDPs.
That sounds right. The network interface needs a way to tell the machine to restart.
On a VAX, the Unibus doesn't do that. In theory you could have a console front end
processor that implements MOP Boot message handling and does the restart if it sees one.
(The same would be true on PDP-10 or -20 machines that have a front end processor.) In
practice, I don't remember that such a thing was ever done.
paul