On 6/9/2020 11:51 AM, Glen Slick via cctalk wrote:
On Tue, Jun 9, 2020 at 9:04 AM Bill Gunshannon via cctalk
<cctalk@classiccmp.org> wrote:
For the VXT-2000 with an H7109-B the rated voltage and current values
are printed right on the power supply label:
+5.1V, 7.81A
+12.1V, 0.62A
-12.1V, 0.46A
-9V, 0.2A
Fixed width character pinout diagram:
+=================+
-9V | Yellow | Orange | +12.1V
+--------+--------+
??? | White | Black | Gnd
+--------+--------+
+5.1V | Red | Blue | -12.1V
+--------+--------+
+5.1V | Red | Black | Gnd
+--------+--------+
Gnd | Black | Black | Gnd
+=================+
The mystery is the White wire. The power supply label only lists 4
output voltages. The White wire appears to be routed to the Ethernet
daughter board. The measured voltage appears that it might be floating
slightly negative, somewhere around -1.5V when the Ethernet daughter
board is installed and around -5V when it is removed. Maybe it is a
high impedance earth ground connection? It appears to be connected to
the shield of the Ethernet BNC, which measures around 1M-Ohm to the
chassis ground when the power supply is disconnected from the main
board, and around 0.75M-Ohm when the power supply is connected.
As long as we are talking VXT-2000, I have this on file, figure it would
be useful for future googling of the list if
this were here as well.? May be a repeat of info from an earlier post,
or maybe elsewhere.
I didn't save the source of the info, but looks like someone named Matt
Millman did it.
The setup is as follows: HP Envy laptop running MOP boot daemon,
connected to Lantronix LTX-C twisted pair
ethernet to AUI converter (not the same as a twisted pair MAU). This is
then connected to a cabletron coax
MAU with a 10BASE5 vampire tap. The coax runs over to another MAU, which
is connected via an AUI cable to
my VXT2000. I didn't think of it, but it would have been nice to have a
real DEC MAU on the VXT2000, I've
got several DEC h4000's I could have used.
https://www.youtube.com/watch?v=A5T2GlAN2N4
http://tech.mattmillman.com/projects/10base5/
The first link is mine actually. (Hi, I'm Joe from Joe's Vax Repair and
More). I have a VXT-2000 and have had it setup and booting on a few
occasions. I also happened into some 10BASE5 equipment a few years back
and the VXT2000 was one of the only AUI devices I had at the time. I'm
not Matt Millman, but I did reference that site to find the existence of
the Lantronix LTX-C and similar devices.
Now that I have more AUI gear, I plan to put different gear on the
3-node AUI segment (cisco 2511 router, media converter to 10BASE2,
VAXStation 3200) and move the other 10Mb equipment to a 10BASE2 segment.
The whole mess will be joined to the main network via T1 on a Kentrox
CSU/DSU on the 2511.
You can boot the VXT2000 using MOP or BOOTP and TFTP actually. MOP was
the first thing I managed to get working, but BOOTP and TFTP worked
equally well once I had it set up correctly. Unfortunately my bootptab
file is on a roommate's MicroVAX II...
Anyway, see the links section here for the software:
https://terminals-wiki.org/wiki/index.php/DEC_VXT2000
There's also theoretically OpenBSD and NetBSD support for the VXT2000,
but in my experience the netboot stuff is pretty broken on VAX for
whatever reason. There's at least one bug for the SGEC ethernet chip
driver, and I could only get older versions of the network boot mop file
to load. Of course, the older versions wouldn't support the newer kernel
format, which apparently changed at some point. Or maybe I'm just doing
something wrong.
If the machine in question gets repaired, feel free to contact me with
any questions. If you're familiar with netbooting VAX systems, it's not
too hard to figure out though.
I'll add that the note about the 9V supply being isolated sounds
reasonable. It could be used as the supply for the built-in 10BASE2 MAU
on some units. I can't confirm as my unit has 10BASET instead which has
no requirement for an isolated supply.
