Tag Archives: passion

Christmas in April

Several weeks back, I received a message from one of my favorite teachers. He said that Christmas was coming in April, and that we should get together soon.

Something he had seen on-line practically called my name he said. He ordered one and it had just arrived from Switzerland. It was in kit form and that we would have to put it together and make it work. We made a plan for him to come visit for a long weekend, and we would assemble this electronic computing machine.

I call it a machine because it has mechanical switches, 30 actually – SPST (single-pole, single-throw in electronics jargon). It also has two knobs for rotary encoders, and a power switch. In the old days of computers, we used SPST switches to record ones and zeros – both for specifying an address in memory and loading that address with data. Older computers had tiny incandescent bulbs for indicators, but inexpensive and long-lasting LEDs soon took on that role. And they look way much cooler.

PiDP-11/70 front panel

However, that describes the front panel only – as the rest of the original computer hardware took up multiple cabinets, multiple racks, sometimes a whole room full of equipment. This particular computer’s  ‘engine‘ is actually only a few square inches, and is considerably more powerful than the one it is simulating.

The Raspberry Pi engine

I say simulating, as one of the programs that this new Raspberry Pi hardware can run is a program that can simulate the entire software environment of the world-renown PDP-11/70. This particular setup is known as the PiDP-11.The PDP-11 line of computers was manufactured by Digital Equipment Corporation (DEC) starting in the 1960s, and swept the world as a ‘super-minicomputer’.

This is a nice history of the PDP-11 :

So, let me <POP> the stack back to the mystery teacher at the top of the page. Some of you may know him as Dave Sieg, my (only slightly older) brother. (The older we get, the smaller the difference in age…) However much as our Father taught me about how things work, my brother started me into electronics at the tender age of 2 by introducing me to his robot, and he continues to enlighten me, and I try to reciprocate. I always enjoy sharing with him things I have learned.

“Meet my robot, don’t be scared.”

We spent a lot of time together in college at Ole Miss in the 70s, and collaborated on many projects. He was more focused on video (television) and I was more focused on computers (mostly hardware, but some software). After we left Mississippi we were both involved in ham radio, and sometimes we could chat between California and North Carolina or Denver (for free). So for 10 years he did research & development into computer graphics for movies and advertising (in Hollywood CA), while I traveled the country maintaining big computer systems for DEC – based first in NC, but then transferring to Denver CO.

In 1990 we gave up the big city life and returned to our hometown Kingsport TN. David had established ZFx, Inc and invited me to work with him (and help maintain the computers). We started Tricon.Net in 1994, one of the first regional internet providers. As a crucial step forward in my education, he started me on a path to learn about using and maintaining UNIX computers. That single concept kept me employed until my retirement in 2016, after working for a few defense contractors, and finally 10 years supporting the ISS with NASA.

My brother has known me longer than anyone still living, and I am thankful that we can still collaborate and enjoy each others company. David & I still teach each other tips & tricks about this versatile computer environment. Kindof like last month when we got together to build this kit, and actually made it work. I love you more than I can express; Thank You David.<RET>

Soldering diodes and LEDs
All switches soldered, ready to test

Returning to the story at hand, we put this thing together one weekend, and had a great time. It works.!. I love it. I can’t count the hundreds of PDP-11/70s I’ve ever worked on during the decade of my life I devoted to DEC. Currently my PiDP-11 is running the default idled program, and makes a neat desktop appliance with many blinky-lights. However, I can set a number in the switch register, and press the address rotary encoder and the simulation can change to any of the PDP-11 operating systems (DOS-11, RT-11, RSTS-7, RSX11mplus, or any of several early UNIX systems). It can even support serial ports for your VT-100s.!.

Choose your favorite PDP-11/70 operating environment

One can even enter Octal program code from the switch register, if you remember any of your assembly language programming.

A short video from Dave to show the ‘idled‘ program in operation.
(this link is to my SomeNet.NET webserver, I can’t upload video here with a free account)

Here is the detail on the PiDP-11:

If this appeals to you at all, make an inquiry.
The web site claims over 3000 kits sold, so get in line – might need wait a bit.
If the PDP-11/70 meant anything to you, this kit might be what you’ve been missing.


Teaching an old dog

Things change so quickly, especially at my age.
Once upon a time I had good control over how the blog thing here was working.

current workspace in my ‘lab’

Years go by, and things change. I have spent several days re-figuring-out the WordPress editors and how they deal with old legacy widgets, and theme options. Kinda like going back to work…

That being said, I have changed (more than) a few things around, trying to preserve as much of the previous functionality as possible. I’m still hoping to be able to continue to use the “blogroll” widget, even tho they discourage sharing links of our friend’s pages… (reduces your ‘ranking’ in Gooooogle searches).

There is still some old stuff on here to be cleaned out, but this is a great start towards rejuvenation.
Feedback greatly appreciated, subscribe if you are even slightly interested.
Promise to not blow up your INBOX.


So, in answer to some that have questioned where I have been, and what I’m doing…

The short answer is “Living“.

A longer answer includes things like : (not a complete list)

.. spending more time taking care of my own agenda.
.. spending even less time looking at headlines.
.. not spending as much time on FaceB**k.
.. we have tomatoes, zucchini, & peppers started in our small patch.
.. adjusting and cleaning up my ham radio VHF antenna stack.
      (in part to make it more “HOA friendly“)
.. further reducing an impressive collection of the trinkets of my life.
.. parsing thru hundreds of old photos, scanning a few – pitching some.
.. reviewing multiple file drawers of papers I have saved since the 70s.
.. but the list grows longer each day – so love being retired.
.. OH, not to mention re-learning the WordPress editor of the day.

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Field Day 2015

I don’t recall exactly, when the last time was that I operated Field Day primarily from home. I haven’t had much setup at home lately, and have been involved with various club efforts for years and years. This year tho, I was “1 Dog from Alabama” – referring to the “1D” category of a home station using commercial power. I used this as an opportunity to exercise one radio with one antenna. I often have my tape measure tuned radial elements on display, but don’t get to use them much at home. I thought 40m was greatly improved. I use these on a Hustler 5BTV, with a Yaesu FT-897D. Conditions were good on 40m thru the night, worked nearly everybody that I called back to. I got good reports.
There had been some concern, that the recent solar storm might leave a mess, but I thought conditions were pretty good. I was pleased.
I worked only the 40, 20, 15, & 10 meter bands, SSB only.
I didn’t get in any hurry, didn’t even leave the house. Made about 50 contacts.


I appreciate N3FJP’s programs; n3fjp.com

I didn’t have a current version of http://n3fjp.com/fieldday.html, but a quick visit to the site, and an install – and it was registered and running. Shows me that ~40% of my contacts were on 7 MHz, but all together fairly well spread about the map. Hope everyone else had a good time as well.


52 contacts on a section map

Thanks for the QSOs…