ISO: PDP-11/40 LTC and Stack Limit options

allison ajp166 at
Mon Nov 21 17:56:24 CST 2016

On 11/21/2016 05:44 PM, william degnan wrote:
> On Mon, Nov 21, 2016 at 4:58 PM, Jerry Weiss <jsw at> wrote:
>>> On Nov 21, 2016, at 2:13 PM, william degnan <billdegnan at>
>> wrote:
>>> On Mon, Nov 21, 2016 at 2:37 PM, Josh Dersch <derschjo at> wrote:
>>>> Hi all --
>>>> I'm finally turning my attention back to my 11/40 (which I started
>> working
>>>> on 7 years ago and never quite got around to finishing -- I've learned a
>>>> lot since then and I'm hoping to be able to debug it properly now).
>>>> My ultimate goal is to run V6 or V7 UNIX on it -- I have the MMU but I'm
>>>> looking for an M787 (line-time clock) and M7237 (stack limit register)
>> to
>>>> complete the set.  I have other DEC stuff for trade, drop me a line...
>>>> Thanks!
>>>> Josh
>>> Just curious, are you aware whether these two are required to boot a RL02
>>> disk or certain versions of RT-11?  I have been experiencing
>> difficulties,
>>> I only have the m737 iinstalled in my system.
>>> Bill
>> RT11 will run w/o an LTC.
>> TTBOMR the stack limit register is not need for Single Job and the
>> other RT11 OS variants.  However a  program could overwrite the vector area
>> and cause an ungraceful shutdown.      Make sure the jumpers on the KD11-A
>> are set
>> correctly for this configuration.
>> Using an RL02 to boot RT11 should be okay as well.
>> Jerry
>> jsw at
> Not exactly what TTBOMR is but I can say that given zero luck booting RT-11
> from an RL02 on my 11/40 my next move is to emulate a TU58 drive on a 2nd
> serial card and run XXDP.    I can run BASIC with no problem, but it seems
> like my known working (elsewhere) M7762 RT11 controller card does not wake
> up when called by the bootstrap 9312 ROM, etc.
> b
Rt-11 must be configured for the controller that boots it at the CSR and
vector its using
(try the standard addresses/Vector). RT has few needs and will run on a
16K machine
with minimal hardware (console and boot device).   I have a 11/2 with
28KW and
DLV11J that boots RT-11FB from TU58 (very slowly but it does!).   That's
a tiny 4
slot Qbus machine (BA11VA) and is very minimal.

Also make sure your trying to boot RT11SJ initially as that has the
lowest needs.


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