11/45 works, but....

[Jay West]

The 11/45 has booted an OS for the first time since I got it. RT11 came 
right up. Interrupts are working. Awesome :) That's actually very satisfying 
because the machine was in very rough shape when I got it.

After fixing the power supply (which was a new problem, unrelated to the 
previous interrupt issue I think), I started growing the configuration back 
to where I wanted it to be in little increments... like adding the BA11K 
back in (with nothing in it, just the 930). Then putting in the M9312, Then 
adding in the unibus memory, RL controller, dropping the core out of the 
picture, etc.... and testing between each small step. It got back to the 
full config and still interrupts are working. So, unfortunately I'm not sure 
what actually fixed the problem which is a little unsettling. But it was a 
big thrill to see the RT11 prompt :)

That being said, I am using a borrowed set of cpu boards. Over the next few 
sessions I plan to start adding my boards back in one at a time and I'm 
betting some of them won't work so I'll still be looking for help to repair 
those (and that will also help me understand the machine better). Note that 
the interrupt problem occured with the same borrowed cpu boards, but now 
it's gone. Odd.

Another oddity reared it's head. The system was very stable with just the RL 
controller. I then installed an RX02 (M8256) controller (and removed the NPR 
jumper for that slot). I turned on the system but left the RL02 turned off. 
The RX02 worked perfectly. Then I turned on the RL02. It powered up ok (no 
fault) but when I spin it up I got a fault light. It is not the drive, nor 
is it the pack. If I shut everything down and leave the RX02 drive powered 
off (but controller still installed), the RL02 will come up fine and not 
fault. So there is apparently something that the RL controller doesn't like 
about the RX02 controller? The NPR jumper is removed for the two slots where 
the RL and RX controllers are, but definitely present in all other slots.

I'm also soliciting advice on memory configuration. The processor has 16Kw 
core in the system chassis. I don't own any MOS/Bipolar. I have two unibus 
64Kw memory boards (M7891 I think it is). My plan was to run the system with 
one 64Kw unibus board, hold the other for spare, and leave the core 
disconnected. I know I can run RT11 ok in 64kw. But based on requirements 
for other things like RSTS, etc... am I better off leaving the 16kw of core 
connected? In other words, for most DEC OS's on the /45 am I going to have 
trouble with 64kw but not 80kw? If it won't make a difference in what I can 
run I'll probably just leave the core disconnected. Thoughts?

Thanks!

Jay West