PDP 11 Line Time Clock (LW11L) M787 and EIS board, (KE11E) M7238

[Josh Dersch]

On 2/13/17 8:16 AM, william degnan wrote:

> Question - I am working on a PDP 11 KE11E M7238 EIS board (for PDP 11/40)
> which causes the CPU to crash when installed; front panel not responsive,
> can't boot XXDP.  I installed a removable jumper so I can flip jumper
> configs back and forth between EIS installed/not installed.  Without the
> EIS the system works fine, can boot OS's that do not require it like RT11.
>
> As discussed before the EIS is required if I want to boot up UNIX 6 on the
> 11/40, which is a goal of mine.
>
> Thought - I don't have a LW11L, M787 installed.  This is a the Line TIme
> Clock option card.  Do you think that maybe the EIS board requires this for
> some reason, even though there are no references to this as a requirement
> in any docs I can find?  Maybe the docs writers assume it's installed?  I
> only wonder because any time I have seen the M7238 installed in an 11/40 I
> have also seen a M787.
>
> I could swap out the current 11/40 backplane with a backplane that has the
> jumpers for the M787 already removed, but I only want to do this if it's
> necessary.  When we were talking before I neglected to mention I had no
> M787, you may have assumed I did.

I think it's extremely unlikely that the EIS requires an LTC to 
function, I can't think of any reason why this would be the case, or why 
it would cause the effects you're seeing.  I also don't recall seeing 
any such requirements in the hardware documentation, but it's been a 
little while since I last looked at them (while installing the MMU and 
Stack Limit Register in my own 11/40).

Can you be more detailed in your description of the behavior you're 
seeing?  Is the system unresponsive at power-up, or is it only after 
attempting to boot that it "crashes"?  Can you toggle in programs and 
run them?

I'll also add that regardless of what's going on  with your EIS, you 
*will* need an LTC to run V6 UNIX so you might think about getting one 
set up anyway.

- Josh

>
>
>
> Bill
>