PDP-11/34 & DG Nova-3

From: David Williams <dlw_at_neosoft.com>
Date: Tue Feb 17 12:16:13 1998

Thanks Tim. I checked out the ftp reference you gave. Great site,
I've already started browsing through a bunch of it.

On 17 Feb 98 at 13:03, Tim Shoppa wrote:

> That connector that you found is almost certainly the Molex
> connector that DEC used for 20 mA current loop connections. On
> older machines, 20 mA was the de facto standard for the console
> terminal, as the console terminal was traditionally a Teletype of
> some sort.

Yes, I've now decided that the console is set for 20 mA. The second
M7856 with that cable seems to be set for both SLU & LTC active set
for console. Transmiter active, receiver active, reader enabled, 110
baud, 8N2. I haven't looked at the switchs for the other board yet.

> All DEC VT-220's came equipped for 20mA current loop, and it was an
> option for the VT-100's and VT-52's. It was also quite standard on
> the older DECWriters.

Guess I need to locate a DEC terminal. I have some Honeywell Bull
terminals which emulate a VT100 and a Wyse 50 but nothing with a
connector which matches this cable. Am I wrong in reading this doc
on the board where it looks like it can be configured for RS-232?
Can I reset it and use a different cable instead of the 20 mA?

> It's possible that you've got a 240V power controller, but unlikely.
> More likely you have a 120V power controller that originally had a
> Hubble 25A Twist-N-Lock connector on it. If you post the model
> number of the power controller box, I can find the voltage it was
> designed for. Usually this is clearly marked on the power
> controller.

I've had a little more time to look over the system. The cut cord to
the power box is real thick and the three wires are a good size too
so I thought it was a 220V connection. Looking a little more closely
at the back of the box I see :

Input 120V 50-60 HZ
2 Pole 3 Wire 24A

> Until then, you'll find that each of the boxes in the rack has a
> rather standard 120V power plug attached. These can be plugged
> straight into whatever you find handy until you get your power
> controller plug reinstalled. The 11/34A CPU box itself draws less
> than 12 Amps.

I'm still finding out things about this system. There is a DEC tag
on the side of the system with the serial number and such labeling it
an 11/34a and dated 16-Dec-77. Not too long after I first started
programing. Back then though I was on HP boxes.

Ok, I need to locate something to use as a console and have the power
supply checked. Then I'll fire her up and see how it goes. After
that I'll begin work on the drive.

David Williams - Computer Packrat
Received on Tue Feb 17 1998 - 12:16:13 GMT

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