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

william degnan billdegnan at gmail.com
Mon Feb 13 12:05:02 CST 2017

On Mon, Feb 13, 2017 at 12:20 PM, Josh Dersch <derschjo at gmail.com> wrote:

> 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

thanks for confirming.  I will turn my attention to the EIS board and set
up a more detailed test/results asap.

More information about the cctech mailing list