[Cryptography] 'The intelligence coup of the century'

[John Young]

At 12:08 AM 2/14/2020, you wrote:
>BTW, IBM mainframes had powerful radio side-channels: in the early
>1960's, one of the programmers that worked with me used to put an
>ordinary portable radio on top of the IBM CPU so that he could
>"listen" to his program go through its paces.  Any change in the
>audio would indicate a problem with the software.
>
>I would guess that this radio technique would have been sufficient
>to enable a person listening to pick out the individual bits in a
>modular exponentiation, as those computers weren't all that fast.
>
>We didn't have a name for it, but in retrospect we should have
>called it 'ADB' -- 'Audio Debugging Bridge'.
>
>I never tested the *range* of these radio signals, but I suspect
>that they could easily have been heard outside the building
>where the computer was located.

Is this a TEMPEST tool, perhaps long used, even now? Ross Anderson aware of it?