MS-NET Redirector for MS-DOS to provide file and printer sharing via the NET USE command. File, Print and Tape servers, for the architecture were also supplied by 3rd party vendors such as S J Research. Econet was supported by Acorn MOS, RISC OS, RISC iX, FreeBSD and Linux operating systems. Acorn once received an offer from Commodore International to license the technology, which it refused. Subsequent development With the falling prices and widespread adoption of IP networking in the early 1990s, Acorn Universal Networking (AUN), an implementation of Econet protocols and addressing over TCP/IP (in Acorn's words "an AUN network is a conformant TCP/IP network underneath the Econet-like veneer"), was developed to provide legacy support for Econet on Ethernet-connected machines. Support for the Econet protocol and AUN was removed from the Linux kernel in 2012 from version 3.5, due to lack of use and privilege escalation vulnerabilities. Supported systems Econet was supported by a large number of different computer and server systems, produced both by Acorn and by other companies. As well as Acorn's MOS and RISC OS these also used other operating systems such as CP/M, DR-DOS, Unix, Linux or Microsoft Windows. The Econet API includes an Econet_MachinePeek command, which can be used by software to determine if a machine is present on the network and its hardware platform. The machine-type codes which can be returned by that command are a useful indication of the range of hardware that offered Econet as their primary networking function or as an option: The manual includes an assembly language program to report a machine type, software version and release numbers. An update to the list in volume 5A of the PRM lists the following additions to the table above: Physical and data-link layers Econet is a five-wire bus network composed of one or more segments (up to 127), where each segment may be up to 500m long. One pair of wires is used for the clock signal to synchronise devices on the network, one pair for data, and one wire as a common ground. In many but not all implementations, a dedicated external board is required to supply the clock signal known as the "clock box", usually positioned in the middle of the network. Some Econet devices have an internal capability to generate the clock signal. Signalling used the RS-422 5-volt differential standard, with one bit transferred per clock cycle. Unshielded cable