No subject

Aaron Jackson aaron at
Thu Sep 23 17:03:55 CDT 2021

Subject: Re: PDP-11/73 boot issues
References: <87ilytoikj.fsf at> <CADBZjLYN9aUTDHJ6=XJwNnNefTUbzyZis4evRS1Coy2r9xcX5w at> <87fstxohuj.fsf at> <edde8fc9-6e38-3215-970f-34b9f3a95ce0 at> <21789e85-2aa4-3b61-db31-b21fd8c08a03 at> <87czp1obv4.fsf at>
User-agent: mu4e 0.9.18; emacs 27.2
In-reply-to: <87czp1obv4.fsf at>

Aaron Jackson via cctalk writes:

> Pete Turnbull via cctalk writes:
>> On 21/09/2021 20:34, Chris Zach via cctalk wrote:
>>> Can an MXV11 be used in a 22 bit system? I thought it was an 18 bit
>>> device?
>> MXV11-B is 22-bit.  MXV11-A is 18-bit but supposedly can be used in a 
>> 22-bit system if the RAM is disabled.
> Yeah this is a 22 bit card. Josh sent me an xxdp image which I could
> easily boot from my scsi2sd (thanks!).  Seems to be reporting an error
> with the CPU unfortunately:
> ]] .R ZKDJ??
> ]] 
> ]] ERROR # =001166
> ]] ERROR PC =040662
> ]] 043632
> This happens regardless of whether W9 is installed or not (supposedly
> disables the LTC register on the CPU?)
> I'll see if I can borrow another CPU card form a friend this
> weekend. Unless anyone else has any ideas?  Another suggestion on IRC
> was to disable the PSU LTC and enable the LTC on MXV11 but will need to
> look up some details on how to do this.

Had a nice cycling trip this evening to pick up a spare 11/73
card. Unfortunately it did not fix my issues so I'll have to do some
more digging.

Has anyone disconnected the BEVENT line and used a signal generator to
provide the LTC? Curious to try this to figure out if mine is just being
noisy or something.


More information about the cctalk mailing list