11/45 RTC

[Tony Duell]

> 
> Julian wrote...
> > How about this: Dig in the KW11-P manual if its available and see if there
> > is any info on replacing a KW11-L with it.  Maybe that will tell you where
> > that LTC L signal is.
> 
> Yes, but I'm missing something somewhere. I see the spot where the power 
> supply LTC L signal hits the cpu backplane. It comes from the brown wire, #7 
> on P2 at the top front. There's a trace that goes down from this to slot 1, 
> row C, pin R1. That's just peachy, and gives me a spot to test in order to 
> make sure the power supply is providing a clock signal.
> 
> But of course I want to make sure that signal is also present on the three 
> unibus slots built into the cpu backplane, so that my DL11-W can use it. So 
> I was looking for THAT pin. From eyeballing it and testing, it appears that 
> slot 1 row C pin R1 (the LTC "source") hits all the unibus slots on the cpu 
> backplane at row C pin D1. Ok, I'm fine there.
> 
> But here's where the KW11-P manual gets confusing. I'm only bringing this up 
> as a sanity check - It says that in order for the KW11-P to get the LTC (if 
> you even want to use that option, not required), you have to install a 
> jumper wire to the slot that the KW11-P is in to provide that signal. It 
> says the KW11-P expects to get it on CE1, and specifically says to run a 
> wire from CE1 to slot 1 row C pin R1 (on the 11/45). But why would they say 
> that if the LTC signal is available on pin CD1 right there in the same slot 
> already next to CE1?? Or better yet, why didn't they design the KW11-P to 
> get LTC from CD1 instead of CE1? This is the part that makes me think I'm 
> messing up somewhere.
> 
> I guess I could find prints for the DL11-W and see if in fact it's looking 
> to CD1 for LTC.


I can't put my hand on the DL11-W prints at the moment (I know I have 
them sowewhere -- several times in fact), but all the notes I can find 
say that the standard pin for the LTC L signal on an SPC slot is CD1. CE1 
is a testpoint, normally unconnected.

In the early days of the Unibus things like this were not standardised, 
so it's quite possible that the KW11-P needs the LTC L signal on CE1. But 
I don't think the DL11-W expects it there.

Can you look at the DL11-W card to see what, if anything, is connected to 
either of those pins?

-tony