I was reviewing a movie from 1975, and it featured a place that brought back memories. It came about this way.
Twenty-six years ago I was looking for a job, and I hired on at a company in Richardson, Texas. It was an interesting bit of enterprise. It was a wholly-owned subsidiary of Chrysler Corporation, and it did military contracts. They were in a rush to get their software done, and they were scrambling to fill in some slots.
I worked that project to death, and this forced my employer to either fire me or to find something to keep my hands busy while they looked for someplace to put me. They told me, “Why don’t you go over and work on the Secure Digital Switch (SDS) project.” I knew the company had this contract, and it was a different kind of work. It was 100% telecommunications. Some elaboration.
Your government does not content itself to operate on the nation’s commercial phone system. they have their own, especially for talk that involves national secrets. So decades ago they re-invented the T1 line, what commercial phone systems have been using since 1962. Since Alexander Graham Bell developed the Bell System in the 19th century voice had traveled over wire in analog form. Your voice is a train of air pressure waves, and for nearly a century telephone sets always converted these pressure waves into electric waves, the peaks and valleys of the electrical waves mimicking the pressure waves of your voice. T1 and later versions in the series carry sounds as trains of numbers, each number representing the value of the pressure wave. A T1 line carries 24 separate voice links along a single wire.
What the United States Government did was to add another channel to carry signaling information. Yeah, there was no way you could tap a commercial line into an SDS wire and make that work. Anyhow, the SDS incorporated a features to not only encrypt the communication channels, but to control which phones could participate in which conversations. If some Air Force majors were holding a conference call with their secret clearance, and the general barged in with his top secret clearance, the switch would drop all phones not cleared for top secret from the conversation.
And that all worked nicely, and my employer had the contract to manufacture and maintain the switches. They also made the phones. See the image above. They are called “red phones” for no good reason, because they are as you can see.
But there was a problem, and I’m guessing nobody else wanted to work on it. And that’s where this place comes in.
That’s the Allied Forces Southern Europe command center in Naples, Italy, and they had one or more of our switches. Secure phone links ran from here to various other bases, and they had a method for testing the links. They would have somebody at the opposite end of a link, e.g., in Germany, break a link and feed it back to Naples. Then they would send out stuff from Naples, and determine the same stuff came back. It’s called a loop-back test. And when the test was completed they would undo what they had done, and the link was usable again. Only there was a problem.
If, for example, the general was talking on the phone to Germany when somebody ran the test he would lose his connection momentarily. Then it would come back and the general would continue talking with a puzzled look on his face.
And sometimes not. Sometimes the disconnect and reconnect would interrupt a control signalling packet, and the switch on the other end would never get it. And the communication link would lock up. Permanently. Have you ever seen a speechless general?
Anyhow, they said, “Fix it.” And I said, “I think I might need some help, like where is the code for the switch, and not only that, where is the code for the line multiplexers?” They said, “Here are some copies of the source code, and, by the way, the code for the switch runs on a Motorola 6803, and it’s in assembly language, and the code for the multiplexer runs on a Motorola 68000, and it’s written in C. And also, there is this guy named Dave on the third floor who used to support this code, but he’s not available to help you, because we don’t have the budget to pay him. You’re on your own.”
The switch had VME boards, which you could pull out and put on an extender so you could get at the circuits while the switch was running. It was necessary to clamp a logic analyzer onto the pins of the processor and track the execution of the code to see what went wrong when the link locked up.
And that’s what occupied the next six months of my life, and that’s why the Southern Command in Naples will always have a dear place in my heart. So when I was watching the movie The Human Factor, and I saw where the George Kennedy and John Mills characters worked I nearly fell out of my seat.
To wrap up the story, I eventually worked out a fix, and I tested it, and it worked. When the connection was broken and reconnected, the new software detected what had happened and fixed things up. The fix required changes to the switch software and the software on two kinds of multiplexer boards. That done, I realized the phones would need to continue to work while people were switching out the software in the switches and multiplexers, so I had to make changes in the phone software. That’s how I got to see the inside of the phone that sits on the President’s desk. Rather, one just like it. The neat thing about these phones is you don’t need to take one apart to change the software. The software is changed by essentially calling up the phone and sending it some special signals along with the new code.
Years later I was doing a visitor’s tour of the Pentagon, and I saw one of the phones on somebody’s desk. I resisted the temptation to pick up the unit and see the company name on the bottom.
The picture is not all that pretty. Before I finished with the phone software I got a better offer from another company, so I dropped by my boss’s desk and gave him my 30-day notice. He assigned another guy to complete the work, and I worked mightily to bring him up to speed. Not only was he too inexperienced, but he had zero fascination for the work. He was, himself, shopping around for another job. I do not know to this day whether the phone software got fixed.