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

Guy Sotomayor Jr ggs at shiresoft.com
Mon Feb 13 11:41:58 CST 2017

If you have a M7856 which is a SLU and LTC on one board you don’t need an

I assume that they you have the EIS board installed, you have the 3 jumper
cables between the EIS and the uCode board.

KM11s will help in diagnosing these issues as it allows you to single step
through the uCode.

TTFN - Guy

> On Feb 13, 2017, at 8:16 AM, william degnan <billdegnan at gmail.com> 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.
> Bill

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