I can not tell you about the oldest running CNC machine, but I can tell you the first time a CNC control was ever shown here in the US.
I worked for Swedish Machine Tool (SMT) and in 1973 they sent us a new control for the Cincinnati Machine Tool Show.
It was a CNC control and it was fantastic.
You could actually write a program into its memory and if it did not work, you could do a thing called Editing, meaning fix your mistakes.
By 1974 we had a 50HP lathe running in the Chicago Show, every Japanese person in the show stopped at our booth to take pictures.
I remenber we had the only CNC lathe in the show that did not stop working, we made parts all through the show.
It was almost impossible to program , but it worked.
To give you an idea how tough it was:
Imagine a 3" diameter:
Add 1.5(the radius) + 5.637(the distance from the tool tip to the turret center), to get the X dimension.
The rear turret was more difficult, if possible.
Fortunately they came up with a better system in Sweden and we sold a lot of machines for really big prices.
Once the Japanese machines came here, read Mori-Seiki, at way lower prices, less than half of ours, we folded.
I had seen the light earlier and learned Fanuc and have been training shops on Fanuc ever since.
Need help, let me know, I travel very little, but still help anyone that needs help.
Heinz Putz.