PDP 11 Line Time Clock (LW11L) M787 and EIS board, (KE11E) M7238
derschjo at gmail.com
Mon Feb 13 11:20:44 CST 2017
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
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.
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