3270 emulator

A 3270 Emulator is a terminal emulator that duplicates the functions of an IBM 3270 mainframe computer terminal on a PC or similar microcomputer.

A terminal window showing white text on a black background. An ASCII art logo reads MUSIC/SP and is captioned below as Multi User System for Interactive Computing / System Product.
A TN3270 client running on Windows

As the original 3270 series terminals were connected to the host computer through a display controller (cluster controller)[a] using coaxial cable, emulators originally required channel (rare), coax or synchronous communication adapter cards to be installed in the PC. Today, many emulators communicate with the mainframe computer through a TN3270 server[b] using the TN3270 (RFC 1576) variant of the Telnet (RFC 495)protocol common on TCP/IP networks including the Internet, so special hardware is no longer required on machines with Internet access. Several vendors offered both coax and communications attached 3270 emulators and TN3270 clients as part of the same product.



In 1983, IBM marketed the IBM 3270 PC, a bundled package including a PC, a graphics adapter, 3270 emulation software and coax interface card. 3270 emulators and TN3270 clients are also available from many third-party vendors like Attachmate and Ericom. Some solutions permitted a coax interface to be shared by workstations in a LAN.

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  1. ^ The original cluster controllers could be directly attached to an I/O channel or indirectly through a synchronous communications link. Later versions also supported Token Ring and Ethernet.
  2. ^ In some cases the TN3270 server is embedded in an adapter, e.g, IBM OSA-ICC, and the emulated 3270 terminals appear to be on a channel attached cluster controller.

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