VAX4000 VLC diagnostics/console

Carlos E Murillo-Sanchez ce.murillosanchez at
Tue Jul 13 22:09:21 CDT 2021

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.
If my understanding of the BlueSCSI and SCSI2SD emulators is right, one 
big difference is that
only SCSI2SD v. 6.0 supports synchronous transfers; all others do not.  
I don't know if a
4000/VLC needs that feature or not.
> 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.
IIRC, in my 4000/60, the MMJ console port is actually RS-422, which 
would require a proper
adapter for it to work with a 232 terminal; is that what the H8571 
does?  I use mine with a vt320.


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