IBM 3270

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IBM 3270

A class of terminals made by IBM known as "Display Devices", normally used to talk to IBM mainframes. The 3270 attempts to minimise the number of I/O interrupts required by accepting large blocks of data, known as datastreams, in which both text and control (or formatting functions) are interspersed allowing an entire screen to be "painted" as a single output operation. The concept of "formatting" in these devices allows the screen to be divided into clusters of contiguous character cells for which numerous attributes (color, highlighting, character set, protection from modification) can be set. Further, using a technique known as 'Read Modified' the changes from any number of formatted fields that have been modified can be read as a single input without transferring any other data, another technique to enhance the terminal throughput of the CPU.

The 3270 had twelve, and later twenty-four, special Programmed Function Keys, or PF keys. When one of these keys was pressed, it would cause the device to generate an I/O interrupt and present a special code identifying which key was pressed. Application program functions such as termination, page-up, page-down or help could be invoked by a single key-push, thereby reducing the load on very busy processors.

A version of the IBM PC called the "3270 PC" was released in October 1983. It included 3270 terminal emulation.

tn3270 is modified version of Telnet which acts as a 3270 terminal emulator and can be used to connect to an IBM computer over a network.

See also broken arrow.
References in periodicals archive ?
With the introduction of Shadow Interface for Enterprise Applications, customers can immediately increase the ROI of their existing 3270 terminal based applications, transforming them into new, Web-enabled business applications, or remodel the transactions into new business logic to use in composite applications based on a service-oriented architecture.
In the late 1970s, IBM introduced the 1403 Braille Printer And, in 1984, the Talking 3270 Terminal was developed by linking the Talking Typewriter's voice synthesizer with a 3270 terminal.
Another alternative would have involved deploying 3270 terminal emulator applications on the 10,000 terminals at the non-IBM mainframe facility.
The server, running on a UNIX or Windows NT platform, starts an X-Direct or Win-Direct 3270 terminal emulation client that is attached to a Multi-Host Coax Gateway.
The new OS also enables the X terminals and Explora's to print from a network printer using NCDterm and NCD 3270 terminal emulators - previously they could only print from a locally-attached printer.
After the appearance of personal computers, the 3270 terminal was replaced by a 3270 emulator running on the user's PC.
In most cases it is no longer a 3270/coaxial connection but a dial-up connection with the PC using a 3270 terminal emulation package or a direct minicomputer-to-mainframe link (3270/coaxial).
The system utilizes our proprietary software protocol that can multiplex more than a hundred 3270 terminal sessions over a single 3270 coax.
This was followed in 1990 with the introduction of the first Windows-based 3270 terminal, which provided convenient access for PCs to host applications.
The traditional user interface to mainframe environments is through a 3270 terminal and IBM's Interactive System Productivity Facility (ISPF), a non- intuitive interface that can be hard to learn.
Interface rejuvenation--3270 terminal interfaces were originally designed for knowledge workers familiar with both the 3270 terminal paradigm and the internal workings of the enterprise.