Good point. While we were not as dependent on electronics at t he time, we need to remember that in the late 60’s and early 70’s, both the Soviets and the US conducted near-earth space detonations of nucs. No major disruptions were experienced as far as I know. I’m skeptical, but would rather not actually have the experience.
No theY didn't.
The treaty banning nuclear weapon tests in the atmosphere, in outer space and under water, often abbreviated as the Partial Test Ban Treaty (PTBT), Limited Test Ban Treaty (LTBT), or Nuclear Test Ban Treaty (NTBT) is a treaty prohibiting all test detonations of nuclear weapons except underground. It was developed both to slow the arms race (nuclear testing was, at the time, necessary for continued nuclear weapon advancements), and to stop the excessive release of nuclear fallout into the planet's atmosphere. It was signed by the governments of the Soviet Union (represented by Andrei Gromyko), the United Kingdom (represented by Sir Alec Douglas-Home) and the United States (represented by Dean Rusk), named the "Original Parties", at Moscow on August 5, 1963 and opened for signature by other countries. It was ratified by the U.S. Senate on September 24, 1963 by a vote of 80 to 19.