advice / suggestion wanted PDP 11/40 only boots XXDP, not RT11

[Fritz Mueller]

> On Jan 31, 2019, at 12:26 PM, Bill Degnan via cctech <cctech at classiccmp.org> wrote:
> 
> My PDP 11/40 suddenly lost it's ability to boot RL02 disks except the XXDP
> disk.  I have two drives, both boot up an XXDP (I have more than one) just
> fine, but any formerly-working RT-11 (v 5, 5.1, 5.3) no longer boots, it
> just hangs.

I'd check things related to interrupts.

My experience has been that XXDP monitors (at least the earlier ones) use polling, and can be boot and run even when disk controller interrupts aren't working because of this.

	--FritzM.