PDP-11/73 boot issues

[Aaron Jackson]

> 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??
> ]] ZKDJB2.BIC
> ]] 
> ]] ERROR WHILE TESTING BOARD FUNCTIONS
> ]] 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.
>
> Thanks,
> Aaron

Probing the BEVENT line and it was 50hz etc, but then I realised it
wasn't actually the right voltage. Replaced a transistor and now it
boots!

Cheers,
Aaron