Datanetics DC-70 is a low-profile keyboard switch. Design work commenced in late 1977; the switch appears to be intended as a low-cost design to address anticipated cost reductions in computer terminals.
Meryl Miller left Datanetics before it entered production, and no DC-70 literature is so far known to have survived. Meryl noted that Mike Muller “had a more or less ‘secret’ project he was working on that supposedly would yield a yet lower or thinner profile keyboard.”
What we do know is that TEC Inc. bought DC-70 from Datanetics around January 1986; the following is an incomplete transcript of the inaccurate OCR version of the Arizona Republic newspaper article from 22nd of January 1982:
TEC Inc. buys keyboard line
… know-how, as well as the equipment and tooling required for immediate production. TEC is producing the DC 70 keyboards for Datanetics' customers. It manufactures video-display terminals for the computer-peripheral market and electronic components for the computer and process-control industries, as well as performing subcontract-assembly work for large corporations. TUCSON TEC Inc. announced Thursday that it has purchased a line of DC 70 keyboards from Datanetics Corp., an International Telephone and Telegraph Corp. subsidiary in Fountain Valley, -Calif. The dollar amount of the sale was not disclosed. TEC is producing the line of mechanical-switch keyboards at its Tucson plant. The keyboard is aimed at manufacturers of home-computing equipment, terminals and small-business systems. The agreement calls for sale of the related engineering and manufacturing data and …
The most likely candidate for this type is ITT snap-action array. This type was used in some early Apple II computers, as the RFI-compliant keyboard. A search for patents naming Michael Muller as the inventor and TEC as the assignee only yields a single patent, US patent 4316066, filed by ITT in November 1980 with a priority date of September 1979 and naming Michael Muller, Reed A. Palmer and Harry R. Marker as inventors. There is also a corresponding German patent filed by International Standard Electric Corp, an ITT subsidiary. Both of these patents were subsequently transferred to TEC; the US patent was transferred in 1984.
As such, it seems fairly likely that this is indeed DC-70.