The 3270 family of terminals

This chapter helps you to understand 3270 facilities and operation, so that you can use these terminals to best advantage in creating the end-user interface for your application. Some appreciation of the 3270 is also crucial to understanding BMS, because so many facilities of BMS exploit features of the 3270.

The 3270 is a family of display and printer terminals, with supporting control units, that share common characteristics and use the same encoded data format to communicate between terminal and host processor. This data format is known as the 3270 data stream.

The 3270 is a complex device with many features and capabilities. Only basic operations are covered here and the emphasis is on the way CICS® supports the 3270. For a comprehensive discussion of 3270 facilities, programming and data stream format, see the IBM® 3270 Information Display System Data Stream Programmer’s Reference manual. Programmers using terminal control commands still need to consult the IBM 3270 Information Display System Data Stream Programmer’s Reference manual for details. The IBM CICS/OS/VS 3270 Data Stream Device Guide also contains much important information. It is primarily intended for programmers using terminal control, but contains information that may be helpful for BMS programmers as well. BMS support for a few special features is discussed in the BMS chapter. (See page Support for special hardware for more information.)

Although the discussion in this chapter is focused on display terminals, most of the material applies equally to 3270 printers. A 3270 printer accepts the same data stream as a 3270 display and simply delivers the screen image in hardcopy form. Most of the differences relate to input, which is (mostly) lacking on printers.

However, additional formatting facilities are available for use with printers, and there are special considerations in getting your printed output to the desired printer. For more information see CICS support for printing.

This chapter describes:

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