[HECnet] Bringing up a MicroVAX 3100-80

[Jason Brady]

Hello,

When I purchased a DEC 3000 with MMJ console connectors, before the MMJ
cables arrived, I created a makeshift connector by cutting off part of an
RJ-45 connector leaving 6 wires. Filed off the clip and smoothed all four
sides.

Wiring as follows for makeshift MMJ to DB9:

Pin 1 Blue DTR to Pin 6 DSR
Pin 2 Orange TX to Pin 2 RX
Pin 3 Black TX Gnd to Pin 5 GND
Pin 4 Red TX Gnd to Pin 5 GND
Pin 5 Green RX to Pin 3 TX
Pin 6 Yellow DSR to Pin 4 DTR

On DB9, leave 7, 8 and 9 unconnected (RTS, CTS and N/C).

Makeshift MMJ from front:  Pins 1 thru 6
DB9 connector from front: Pins 1 thru 5 on top, Pins 6 thru 9 on bottom

Cable colors may differ depending on the RJ45 cable. Cable worked until the
real MMJ cable arrived.

HTH!

Regards,
Jason

On Thu, Mar 26, 2020 at 5:14 PM Paul Koning <paulkoning at comcast.net> wrote:

>
>
> On Mar 26, 2020, at 7:57 PM, Supratim Sanyal <supratim at riseup.net> wrote:
>
> I have obtained a MicroVAX 3100-80 with a Storageworks pizza box, a CD-ROM
> drive, a tape drive, some cables and no monitor.
>
> It powers on, does not smoke or explode. The 8 LEDs at the back settle
> down to all on except 2 and 3 counting from zero on the right. I can hear a
> hard disk spin up.
>
> The cables include two MMJs. I have a PC with a 9-pin female serial
> connector. It runs Linux.
>
> The first two of many questions: does the “0” connector connect to the
> console? What exactly do I need to do to connect the PC’s serial port to
> the MMJ cable? Note: I have passable soldering skills.
>
>
> This should do the job, you just need to verify the pinouts.  A pin
> insert/remove tool might be a good investment to make adjustments in case
> the first choice of pinout turns out to be not what you want.
>
> Next question will be about the BNC connector and networking. One thing at
> a time.
>
>
> That is a 10Base2 connector.  Next to it is an AUI connector.  So if you
> have a 10Base2 repeater or switch, just run coax between the two.  It most
> likely needs a T connector at this end with a terminator on the T (or going
> to other stations if you have more).  The AUI connector could be used
> instead, for example if you have a 10BaseT transceiver that might be
> convenient.  Those are still sold; Amazon lists one from Unicom for $30.
>
> Here are some pictures: https://photos.app.goo.gl/KduorZEimMQ73bMdA
>
>
> Nice!
>
> paul
>
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