What is IBM 5250 (TN5250)

Six years after the 3270 terminal, IBM introduced the 5250 terminal as a block oriented computer terminal (sometimes called display devices) to communicate with IBM mid-series servers. Unlike a character-oriented terminals like VT220 or ANSI, the 5250 minimizes the number of I/O operations required to transfer large blocks of data known as data streams, but requires more computing power inside the terminal itself to handle the complexity of the TN5250 protocol. The IBM 5250 terminal is similar to the 3270 terminal, but less complex.

The 5250 series was designed to connect with IBM Series 400 midrange computers (latter called iSeries), often at a remote location, using the technology then available at the time. Two of the major design goals of 5250s are minimizing the amount of data transmitted (data links were often via 9600 bps modems). In a data stream, both text and control (or formatting functions) are interspersed allowing an entire screen to be "drawn" as a single output operation via Token Ring network.

Although IBM no longer manufactures 5250 terminals, the IBM 5250 protocol is still commonly used via terminal emulation to access iSeries-based applications, especially in mid sized organizations and companies.

Since Token Ring networks are no longer in use these days, today TCP/Telnet is mostly used as a transport, hence the emulation is now also often named in conjunction with the Telnet transport and called TN5250.

ZOC Terminal: Modern TN5250 Emulation

Because of the complexity and because of some arcane features of the TN5250 protocol, most standard Linux/Unix oriented telnet clients can't be used to emulate TN5250 terminals.

ZOC however offers an industrial strength implementation which matches the stability and features of IBM's own TN5250 emulator at a fraction of the price and thus lets you access IBM mainframes via a telnet or SSL connection using the TN5250 emulations (remote login protocols that make it possible to emulate IBM's two terminals).

The ZOC TN5250 Telnet Client includes a number of powerful features. It is highly configurable and includes common terminal features such as full keyboard redefinition and user defined on-screen buttoms.

It also offers some very advanced and unique features such as a powerful script language and automatic triggering of actions based on received or typed text. Besides that, the ZOC Terminal also supports common emulations like vt102, vt220, Wyse, TVI, and Sun's CDE as well as IND$FILE file transfer.

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