IBM 3270 Information Display System
The IBM 3270 Information Display System is a family of block-oriented computer terminals and control units introduced by IBM in May 1971. Designed to succeed the earlier IBM 2260, the 3270 was developed to efficiently interface with IBM mainframes, such as the System/360 and System/370, by minimizing the frequency of I/O interrupts to the host processor. Unlike asynchronous terminals that transmit data character- by-character, the 3270 system utilizes a local buffer and transmits only modified data fields in a single block when an attention key is pressed.[1]
The system's architecture relies on cluster controllers, such as the IBM 3271 or 3272, which manage the communications between multiple display stations and the host. Connection to the controller is typically achieved via 93-ohm RG-62 coaxial cable. The 3270 data stream allows the host to define specific fields on the screen with distinct attributes, including protected (read-only), numeric-only entry, and high intensity.[2]
IBM 3270 Family Terminals
The following terminals comprise the official IBM 3270 product line:
- IBM 3275 Standalone Display Station (Models 1 and 2)
- IBM 3277 Display Station (Models 1 and 2)
- IBM 3276 Control Unit Display Station
- IBM 3278 Display Station (Models 1, 2, 3, 4, and 5)
- IBM 3279 Color Display Station
- IBM 3178 Display Station
- IBM 3179 Color Display Station
- IBM 3180 Display Station
- IBM 3191 Display Station
- IBM 3192 Color Display Station
- IBM 3194 Color Display Station
- IBM 3290 Information Panel (Gas Plasma Display)
Compatible Terminals
The dominance of the 3270 architecture led to the creation of a large market for plug-compatible terminals from third-party manufacturers. These devices were designed to emulate IBM hardware while often offering additional features or lower pricing.
Manufacturers and models included:
- AT&T Teletype: 4540 and 5540 series
- Beehive International: DM3270 and ATL-078
- ITT Courier: 270 and 9000 series terminals
- Lee Data: 1221 "all-in-one" terminal
- Memorex Telex: 1377 and 2078 series display stations
- Raytheon Data Systems: PTS-100 and PTS-2000
References
- ↑ IBM Corporation (May 1971). "An Introduction to the IBM 3270 Information Display System". Bitsavers.org. http://www.bitsavers.org/pdf/ibm/3270/GA27-2739-1_An_Introduction_to_the_IBM_3270_Information_Display_System_May71.pdf. Retrieved February 27, 2026.
- ↑ IBM Corporation (May 1971). "IBM 3270 Information Display System Component Description". Bitsavers.org. http://www.bitsavers.org/pdf/ibm/3270/GA27-2749-0_IBM_3270_Information_Display_System_Component_Description_May71.pdf. Retrieved February 27, 2026.
