VAX4000 VLC diagnostics/console

Douglas Taylor dj.taylor4 at
Tue Jul 13 16:34:45 CDT 2021

On 7/13/2021 3:30 PM, Adrian Graham via cctalk wrote:
> Hi folks,
> I'm testing a little BlueSCSI adapter (BlueSCSI <>) which
> while being aimed at 68K Macs should also work as an 8 bit target for older
> VAXen, it's a newer cheaper SCSI2SD solution and I should point out it
> works as intended on a Mac Plus so the module itself is fine.
> Nobody appears to have tested on small VAXen yet so tonight I dug out my
> VLC to give it a go.
> 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.
> Cheers,
There are 2 ways to have a console on the VAX4000/VLC.  A switch on the 
back selects either; (1) graphics console mode, or (2) terminal attached 
to the serial port.  It sounds like you have the switch set to graphics 
console mode, in that case you get nothing from the serial port.

I can't remember where the switch is on the back, bitsavers or someone 
who remembers can help.


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