The 3270 family of terminals

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 IBM 3270 Data Stream Programmers Reference. IBM 3270 Data Stream Programmers Reference also contains important information. It is primarily intended for programmers using terminal control, but contains information that might be helpful for BMS programmers as well. BMS support for a few special features is discussed in Support for special hardware.

Although this discussion 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 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 intended printer. For more information see Printing and spool files.