IBM 5250

IBM 5250 was originally a name for a series of terminal devices that were shipped with the minicomputers IBM System / 3, System/32 and System/34. Later they also used for computer of the type System/36, System/38 and AS/400 for. In addition to the hardware designated 5250 and the protocol used to transmit the data at this point.


Similar to 3270, there is a block-oriented terminal protocol. The 5250 data stream sends special markup elements as byte information by which, for example, the boundaries of input fields and colored highlighted areas are defined. A status of whether the system is busy with a request is given. Over time, the 5250 definition has been extended to now are standard GUI elements like checkboxes, context menu or the treatment of mouse events available.

Hardware - 5250 terminals accept connections to the host computer via twinax cable. This connection is, however, become rare because nowadays there is a wide variety of PC and Web-based emulation programs to dispositions that are able to interpret the data stream. Some emulation packages like IBM iSeries Access feature, besides their actual representation of many additional features such as a complete graphical system administration, support for file transfer operations, macros, client-server database access or a printer emulation.

Telnet 5250

In Telnet 5250 ( TN5250 ) are the transfer of a 5250 data stream using the Telnet protocol. Also, the software used for this purpose is referred to as TN5250. Here, the emulator can be used using the TCP / IP protocol instead of SNA. ASCII Telnet clients ( like xterm or the MS Windows supplied telnet.exe ) can not be used as a substitute for TN5250 clients because of the fundamentally different structure.

Known TN5250 clients

  • Host Explorer ( Hummingbird )
  • Host Access ( | Rogue Wave)
  • Quick3270 (DN- Computing)
  • MochaSoft TN5250 ( MochaSoft )
  • Reflection ( WRQ )
  • System i Access
  • TN3270 Plus ( SDI)
  • TN5250 - free and open source 5250 terminal and printer emulator
  • TN5250J - 5250 client implementation written in Java
  • Xtn5250 - free and open source 5250 terminal emulator written in Java
  • Z / Scope Express 5250 ( Cybele Software )