Subject: Re: What terminal for console?
To: Rick Copeland <rickgc@calweb.COM>
From: Tim Shoppa <>
List: port-vax
Date: 02/07/1997 09:27:16
> On a MicroVax 3600 what terminal could I use as a console monitor?  There
> appears to be a "RJ12" jack in the front of the cpu module which I expect is
> the console input/output.  
> Rick GC

Any RS-232 and/or DEC423 terminal should work fine.  Note that the
jack isn't quite a standard RJ-series jack; the latch is offset to
the side.  These connectors are known as "Modified Modular Jack" or
"MMJ" or "offset modular" connectors in various catalogs.  If you
don't have ready access to a source of these connectors, you can take
a regular RJ-series jack, break off the latch, and file it down so it'll

The pinout is given in the comp.unix.ultrix FAQ:

26. What are the pinouts of the MMJ jacks on the back of various DECstations
        and VAXstations?

This describes the 6-pin modified modular jack (MMJ) used for serial ports
on various DECstations and VAXstations, as well as on other DEC equipment.

DEC carries four DB-to-MMJ adaptors.  They are internally wired as follows

                   Rdy Out  TX+  TX-  RX-  RX+  Rdy In
 Adaptor   Gender     1      2    3    4    5     6       Use with:
 H8575-A     F      20      2    7    7    3    6&8     VTxxx terminal
 H8571-C     M       6      3    7    7    2     20     DEC printer
 H8571-D     M       6      3    7    7    2     20     Modem
 H8571-E     M      20      2    7    7    3    6&8     Female terminal
                                                        or LaserWriter

RS-232 using DB-25 connectors:
                                                DTE           DCE
                                             Terminal        Modem
                                            or computer
Pin Number Signal Name
    2          TD        Transmit Data                   -->
    3          RD        Receive Data                    <--
    7          GND       Ground                          ---
    6          DSR       Data Set Ready                  <--
    8          DCD       Data Carrier Detect             <--
   20          DTR       Data Terminal Ready             -->

Tim. (