On interfaces, paper tape readers/punches,

[Brent Hilpert]

"Roy J. Tellason" wrote:
> I do indeed have a board around here someplace that I have no info on,  but
> it's got a row of those -- 12? -- and the outputs of them seem to be coupled
> to a couple of 7400 chips.

..early DTMF decoder perhaps? (although the count should be 7 or 8 for DTMF).
Alternatively, some proprietary radio signalling/control stuff used multiple tones.