After establishing that commercial operation of "value added carriers" was legal in the U.S., Bolt Beranek and Newman (BBN), who were the private contractors for constructing packet switching nodes (Interface Message Processor) for the ARPANET, set out to create a private sector version.
In January 1975, Telenet Communications Corporation announced that they had acquired the necessary venture capital after a two-year quest.
[11] By contrast, a typical microprocessor-based system of the time used a bus; switched fabrics did not become common until about twenty years later, with the advent of PCI Express and HyperTransport.
Improvements in the software allowed new tables to be loaded, but the network never used dynamic routing protocols.
Roberts and Barry Wessler joined the international effort to standardize the a protocol for packet-switched data communication based on virtual circuits shortly before it was finalized.
A few minor changes, which complemented the proposed specification, were accommodated to enable Telenet to join the agreement.
[nb 2] The main internal protocol was a proprietary variant on X.75; Telenet also ran standard X.75 gateways to other packet switching networks.
Organizations with a large number of local terminals could install a TAC on their own site, which used a dedicated line, at up to 56 kbit/s, to connect to a switch at the nearest Telenet location.
In this sense, PC Pursuit was similar to the Internet, allowing any user to call any system as if it were local.
On connection to the network, the user entered a 5-letter code for the target city they wished to call.