> I was wondering if anyone here can help me with the construction of a
> cable designed to hook up the serial port to a PC.  Now I can figure out
> the PC side of things fine, but I'm not sure of the pinout for the vax end
> of things.

>From the comp.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             -->

This is the MMJ pinout:

   Pin     Signal
    1      Data Terminal Ready (DTR)
    2      Transmit Data
    3      Ground (Ref to Xmt Data)
    4      Ground (Ref to Rcv Data)
    5      Receive Data
    6      Data Set Ready (DSR)

   Do you see a pattern here? A loopback connector that DEC has is connected:
   1<>6, 2<>5, and 3<>4.

>  How would I do it? I've been told that most people use an
> RJ-11 and shave off the connector bit until it fits in the proprietory DEC
> socket.i

Or you can buy a MMJ plug from your local electronics store, or you
can order one from Digi-Key (Digi-Key part #A9057-ND, AMP part #5-555237-2),
or you can pay me to make a cable assembly for you.

Tim.