Vendor lineage
Micom - concentrators, and what they were really selling
Fewer leased lines for the same number of terminals, which is an argument a finance director understands.
Micom was founded in 1975 by Stephen Bernard Dorsey and built its business on data concentrators - equipment that let many terminals share one circuit instead of each needing its own. It was sold to Philips in 1984 and acquired Spectrum Digital in 1987.
James L. Pelkey's history of computer communications records an earlier chapter than the corporate register does: American Data Systems came apart between 1970 and 1972 and the enterprise re-emerged as Micom, which went on to be one of the era's larger successes. That is the rarer shape in this timeline - most entries here were acquired and absorbed, and a company that failed and came back under another name is a different story. The account is Pelkey's, and his history gives it two numbered sections - the collapse at §5.11 and the rebirth at §7.6 - which is a more precise citation than the corporate register offers, since no register reachable here carries the connection at all.
The concentrator is the clearest case in this period of a product sold on arithmetic rather than on capability. A leased line was a recurring cost and terminals were idle most of the time; a box that let eight terminals share one line paid for itself against the line rental, and the technical argument barely had to be made.
That shape recurs constantly in networking and is worth recognising: the products that spread fastest are usually the ones whose benefit can be written as a subtraction on somebody's monthly bill.