3270seeria

3270seeria is the Finnish designation for IBM's 3270 family of mainframe display terminals. Introduced in the early 1970s, the line used the 3270 data stream, a block-oriented protocol that supported screen-based interaction with IBM System/360 and its successors. Displays commonly offered 80 columns by 24 rows and used field-level attributes to manage input, including protected fields, highlighting, and cursor positioning.

Operation relies on a local display buffer; the host sends screen images via the 3270 data stream, and the terminal redraws only changed regions. Input is collected through a keyboard with function keys and Attention Identifier keys that generate commands in the data stream, such as Enter or Clear. Early versions connected through dedicated channels or display controllers; later models supported networked interfaces and SNA-based control units.

Notable models in the 3270seeria include the 3278 and 3279 display units. The 3278 was usually monochrome; the 3279 added color variants. These devices supported enterprise-scale data entry and retrieval, used in sectors such as finance and government, and formed the backbone of many line-of-business applications for decades.

With the rise of graphical terminals and PC-based emulation, direct hardware terminals became less common, but the 3270 data stream persisted. Modern access uses TN3270 or 3270 emulators to connect to z/OS and other IBM systems, maintaining the familiar mainframe interaction model in a software-based form.