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

william degnan billdegnan at gmail.com
Mon Feb 13 10:16:54 CST 2017

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.


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