Editing IBM 3270 (section)

==Third parties==
One of the first groups to write and provide operating system support for the 3270 and its early predecessors was the University of Michigan, who created the [[Michigan Terminal System]] in order for the hardware to be useful outside of the manufacturer.{{clarify|date=August 2017}} MTS was the default OS at Michigan for many years, and was still used at Michigan well into the 1990s.
Many manufacturers, such as [[GTE]], [[Hewlett-Packard]], [[Honeywell]]/Incoterm Div, [[Memorex]], [[ITT Corporation|ITT Courier]], [[McData]], Harris, [[Alfaskop]] and [[Teletype Corporation|Teletype]]/[[AT&T]] created 3270 compatible{{efn|Some, such as the GTE IS/7800, were not fully compatible.}} terminals, or adapted ASCII terminals such as the [[HP 2640]] series to have a similar block-mode capability that would transmit a screen at a time, with some form validation capability. The industry distinguished between 'system compatible' and 'plug compatible' controllers, where 'system compatibility' meant that the third-party system was compatible with the 3270 data stream terminated in the unit, but 'plug compatible' equipment was also compatible at the coax level, thereby allowing IBM terminals to be connected to a third-party controller or vice versa. Modern applications are sometimes built upon legacy 3270 applications, using software utilities to capture ([[Data scraping#Screen scraping|screen scrape]]) screens and transfer the data to web pages or GUI interfaces.

In the early 1990s a popular solution to link PCs with the mainframes was the [[Irma board]], an [[expansion card]] that plugged into a PC and connected to the controller through a coaxial cable. 3270 simulators for IRMA and similar adapters typically provide file transfers between the PC and the mainframe using the same protocol as the [[IBM 3270 PC]].<ref>{{cite magazine |last=Spiegelman |first=Lisa |date=1986-12-22 |title=3270 Emulation Market Growing, Analysts Say |magazine=InfoWorld}}</ref>