Re: Can you MOP boot an install kernel directly?

[Paul Koning <paulkoning%comcast.net@localhost>]

> On Aug 4, 2025, at 10:45 AM, Johnny Billquist <bqt%softjar.se@localhost> wrote:
> 
> I'll just top-post to be lazy.
> 
> First of all, as you know, MOP is the "native" way to netboot DEC machines from back in the day. And MOP sortof fills the place of both DHCP and TFTP in one. But it's more targeted for the explicit need of netbooting and remote management. But in a sense, for VAXen, it would be great if we had the possibility of getting all the netbooting though MOP and not need DHCP and TFTP. Not sure if that is possible, though.
> 
> I guess MOP didn't really become that relevant with VAXen until the uVAX II (that one was able to netboot, right?). There were net-bootable PDP-11 systems as well, which also used MOP, and which were earlier. But pretty much all the handling of MOP on those machines were actually located in the ethernet controller itself. The CPU was pretty much just in a tight loop until the controller brought it out of there. But that was primarily for the PDP-11. On VAXen, MOP was implemented in the boot monitors. Not sure you can even use the MOP in the controller itself if you're on a VAX.
> But so, for simh, the controllers do implement at least parts of the MOP on that side. For VAXen, with something like the 3900, the boot roms from the actual machine are included, if I remember right, and so MOP booting will definitely work there no matter what else simh might do.
> 
>  Johnny

I don't think that's entirely accurate.  From the Ethernet device point of view, MOP packets are just packets, it doesn't know or care what they mean.  (Well, with the exception of the "trigger" packet, for that to be supported requires the device to check for it and yank on the reset line if one is seen.  Not clear if VAXen ever did this, but I think PDP11s can do this at least with a DEUNA.)

MicroVAX would certainly be an example of a system able to use MOP.  It was, I believe, the engine in the LPS40 laser printer, which was netbooted as far as I can remember (into VAXeln, not VMS or NetBSD).

	paul