DG S/130 progress

Henk Gooijen henk.gooijen at hotmail.com
Thu Oct 15 11:54:35 CDT 2015

Henk wrote...

>Great series of pictures Jay!

>>Thanks! Most of those pics are "so I don't forget where wires go", but
>>some of them are presentable :)

I am used to make notes and draw sketchy pictures to remember how cables
were connected. But then, I try to re-install all cabling within a week.
My memory is not yet completely faded in a week, and the drawings do
the rest :-)  When I started collecting back in 1996 or so, I did not
have a camera, so drawing was the only option. I still have drawings of
the PSU and cable harness for the 11/35 from back then.

>>After more than a year on a desk, I mounted the 6125 tape drive in the
>>top of the rack with its power supply on the right side next to it.

>I went to mount my 6125 today, but alas I may have to get creative.
>My 6125 was in a "desktop" stand, and when I remove the power supply
>and also look at the DG Installation docs - it appears that they used
>a different sheet metal backing to mount the 6125 in a rack (on the side,
>as you say) rather than on the desktop unit. I was sooo hoping to just
>remove and mount. Well, either they used different metal or my vertical
>posts are spaced different than expected. I don't think it's the latter,
>because all the measurements matched with the installation guide for the
>cpu and the 6030 disk unit.
>Hummmm.. looking at pictures... it's the former. The sheet metal the PS
>is mounted on is definitely shorter (left to right) on mine than what is
>pictured. I guess I now have a use for the metal brake that I just bought
>yesterday that is still in my car ;)

LOL. I also drive for weeks with stuff in the back of the car.
Not because I forgot it ... just waiting for a tactical moment to get it
from the car into the house ;-)
I can only tell about the 6125 that I have. Perhaps there are other methods,
but the drawings and doc that I have (from Bruce, tnx!) match my config.
On the right vertical post of the rack you mount two hinges. Each hinge has
a pin that simply goes through a hole of the vertical post, and one screw.
The screw (Allen type) is at the front side, you have to remove the pin of
the hinge (screw). After you mount the two hinges on the right side vertical
post, you can mount the 6125 tape drive. Yup, the entire tape drive hangs on
those two hinges. The form the pivot to swing the tape drive in and out of
the rack. That's why the horizontal circuit board has that rounded shape!
On the tape deck, at the left side is a hole for a screw to lock the tape
drive in the rack. The screw simply fits a hole in the left side vertical
The power supply is mounted at the right side (seen from the front) in the
rack, using a metal plate from front to rear vertical post. The drawings
indeed show two versions. The difference is the length of the metal plate.
The distance between components on the horizontal circuit board of the
tape drive and the bottom of the PSU cage is just ~0.5".
Long story. If you like, I can take a set of pictures on Saturday.

>>Indeed!  I feel like being spoiled by DEC with connectors for everything.
>Anything I would say to that would probably start a flame-war between
>DEC and DG enthusiasts, so I'll just leave that one alone ;)

Ahh yeah, but that was not my intention. They are different companies,
so they have different ways of doing things, although quite similar.
The one does not have to be better than the other, but my (first)
impression is that DEC stuff is a little easier. But then, I am a
"newbie" in DG land.

>>I have the controller board for the 6125, but I do not have the cable
>>from the backplane to the paddle board. I *think* I do have the cable
>>from the paddle board to the pin header on the 6125 board (the
>>horizontally mounted one).
>As Bruce pointed out to me, there are actually only a few different
>backplane wirings. Since it hasn't been rackmounted yet, I haven't gone
>searching all the DG racks to see if I have any of the internal or
>external or device cables for the 6125. We'll see. I suspect I will
>have to make all my own cables; all my DG gear came from two collectors
>in separate acquisitions - with one exception. This 6125 I bought off a
>shelf at the local electronics haunt years ago, and it had no cables.

As far as I know, there is one pin header on the horizontal circuit
board for connection to the controller and one cable on the vertical
board that goes to the PSU. The other side of the PSU (rear in the rack)
has the mains power cable (cannot be detached).

Yes Bruce is a most-helpful guy ++. I hope to be able to return a favor.
I am told that the disk in the NOVA 3 has a COBOL environment (compiler),
and the NOVA 4/C that I picked up today has a manual of BUSINESS BASIC.
The application on the NOVA 4 is an accounting system written in BASIC.
The complete listing is also in the doc, so expect the interpreter to
find as well on the disk.
I still have to do an inventory of what the system contains, but from
memory I saw it is a NOVA 4/C (or was it "S"?). In the bottom is a
fixed disk drive. It does not have a top for a removable cartridge,
it is a hard disk only. Capacity 12.5 MB according to the doc. On top
of the hard disk drive is mounted one 8" floppy drive. It IS bolted
onto the top of the hard disk. The interface cable of the hard disk
and the cable from the floppy disk both go together to one single
typical DG edge connector. The doc says that the floppy drive is 1.2 MB.
Below the slit for the floppy is a large small rectangular push button
with an LED in it. I have seen similar floppy drives, but never on DG.
But it is "original" DG, because I have the mating blue front cover with
openings for this floppy drive. The hard disk drive/floppy drive combo
can be lifted by one person, but I would not walk a 100 meter with it.
It is heavy, I estimate between 40 and 50 kilo. Not good for your back,
but when you're on your own (unloading the van) ...

>>My 6125 did power up correctly, but when I mount a tape and press BOT,
>>it spools some tape and then stops. When I press BOT again, it spools
>>again some tape. Did that a few times ... had to manually rewind the
>>tape as REWIND did not work. Could be a missing BOT on the tape, or
>>issues ...
>If there's no BOT tape on the tape, yeah. If there is, I'd look first at
>testing the BOT/EOT sensor. I think there's a procedure for that in the
>manual. ISTR that when it hits the BOT tape, it actually backs up a
>little so it can get a "running jump".

Would love to see that "backing up" :-)  Open reel tape drives still
have the great looks. No wonder you see them in the back spinning in
old SciFi movies (remember Time Tunnel?)

>>Keep posting!  I am a "newbie" on DG stuff with a long road ahead.
>Ditto here, new to DG gear as well. Bruce has been a great help, but
>pouring over docs for hours has been invaluable.

How true! I have nobody in vicinity to talk to about DG stuff. Just like
you, I read docs to know how to mount and connect the 6125.
I'm now reading bits about the NOVA 3 itself, and hope to do some tests
on Saturday. A first check gave me the impression that several bulbs on
the console are burnt out. I hope the system is fine, but not sure
about that :-/

- Henk 

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