Microvax 3100/90 OPA0

From: Pat Finnegan <pat_at_purdueriots.com>
Date: Sat May 25 01:05:12 2002

On Fri, 24 May 2002, Doc wrote:

> On Fri, 24 May 2002, Bob Lafleur wrote:
>
> > My "new" Microvax 3100/90 has 4 serial ports, 3 MMJ's and one DB25-M. The
> > MMJ's are numbered 0, 1, and 3, and the DB25-M is labeled 2. I assume the
> > one labeled 0 is the console OPA0 port. There is a big yellow sticker above
> > the ports that says "0 OPA0" but it has a big arrow pointing to the RIGHT.
> > (the ports are numbered 0, 1, 3, 2 from left to right). This sticker seems
> > to be really odd.
>
> OPA0 is port 3, the rightmost MMJ.

Actually, this depends on the setting of the micro slide switch on the
back of it. One position (BREAK ENABLE, IIRC) uses MMJ0[1], and the other
position (BREAK DISABLE) uses MMJ3. Don't ask me why DEC did such an odd
thing.

> > My MMJ cable should arrive Tuesday. I'm planning to connect to my PC serial
> > port and use a terminal emulator to control the console. I assume I need a

I hope you have better luck than me. I've never had any luck in getting
an MMJ (RS-423?) console port to work right with a PC's serial port, but
it could just be my stuff....

> > null-modem/crossover cable to go from my PC COM port to the MMJ jack...
> > Correct me if I'm wrong.
>
> The MMJ cable is a crossover cable itself. You just need an adapter
> to match up with the PC's serial port.
>
> > Does anyone know if it is possible to use the DB25-M port as OPA0 instead,
> > like you can on the VAXstations? My MMJ will be here on Tuesday, but if I
> > could use the DB25-M, I could get my machine up and running this weekend :)
>
> Not that I know of.

I'm pretty sure DOC is correct on this one. AFAIK you can't use anything
other than port 0 or 3 as the console.

[1] I think this should be 0, but could be 1.

-- Pat
Received on Sat May 25 2002 - 01:05:12 BST

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