VAX4000 VLC diagnostics/console

Adrian Graham binarydinosaurs at
Thu Jul 15 02:50:29 CDT 2021

> On 15 Jul 2021, at 03:42, Doc Shipley via cctalk <cctalk at> wrote:
> On 7/13/21 14:30, Adrian Graham via cctalk wrote:
>> Hi folks,
>> Powering up with nothing attached apart from an MMJ/H8571 cable I get
>> nothing on the console, I'm using PuTTY via a genuine COM1 port on a PC
>> which is one level above what I used last time I powered the machine up
>> (FTDI USB adapter to a laptop). Diagnostic LEDs cycle through the tests and
>> end up at '1111 0011' which according to the manual is 'entering the
>> console program'.
>> Clearly the DALLAS has passed the TOY tests, but if it's not happy would
>> that stop the console displaying? It doesn't matter how I set S3, next step
>> I guess is to hook it up to a 'proper' VT.
>  Adrian, I'm having exactly that problem with my VLC.  I put a Real VT420 on it and still get no output. With a known-good/compatible monitor and keyboard on it, same thing.
>  If there's a solution to this, I'd love to know.

All I did with the VT was connect up with the usual H8575-A MMJ-DB25 adapter, set S3 to up and switch on. Presumably your LEDs are going through the right sequence and end up at 1111 0011? 

Adrian Graham
Owner of Binary Dinosaurs, the UK's biggest private home computer collection?
t: @binarydinosaurs    f:

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