IBM 3270

IBM 3270
Name	IBM 3270
Type	Block-oriented display terminal
Manufacturer	International Business Machines Corporation
Introduced	1971
Successor	IBM 3196
Related	IBM System/370, IBM System/360, IBM 3274

IBM 3270 The IBM 3270 was a family of block-oriented display and printer terminals introduced by International Business Machines Corporation in 1971 for use with IBM mainframe systems such as IBM System/370, IBM System/360, z/OS, MVS. It replaced earlier IBM 2260 technology and influenced terminal paradigms in environments using CICS, IMS, TSO, ISPF applications and enterprise installations at organizations including AT&T, Bank of America, Federal Reserve Board. The 3270 architecture emphasized low host overhead, specialized controllers like the IBM 3274, and widespread deployment in commercial computing centers, data centers, and government agencies such as NASA and United States Postal Service.

Overview

The 3270 family provided display, printer, and keyboard devices designed to work with mainframes from International Business Machines Corporation and to support transaction processing systems such as Customer Information Control System and Information Management System; models ranged from single-screen terminals to cluster controllers and multiuser concentrators like the IBM 3290, IBM 3276, IBM 3179. Its block-oriented design contrasted with character-oriented devices used by vendors including DEC and Honeywell, and it shaped interaction paradigms found in enterprise software from providers like Unisys and Fujitsu.

History and Development

Development began as IBM sought improvements over the IBM 2260 and to meet demand from customers like Bank of America and CERN for interactive access to System/360 and later System/370 hosts. Design work involved IBM laboratories such as IBM Research and connected with standards efforts at organizations like ISO and national bodies including ANSI. Field deployments grew through the 1970s and 1980s as mainframe platforms such as MVS and VM/CMS supported 3270 terminals, and competitors including Wang Laboratories and Burroughs produced alternative solutions.

Hardware and Model Variants

Hardware variants included display terminals (e.g., IBM 3277, IBM 3278, IBM 3279), printers (IBM 3287), and cluster controllers (IBM 3274, IBM 3174). Models differed by screen size, color capability, character repertoire for locales served by companies like Toyota and institutions like Harvard University, and by connectivity options compatible with channel architectures on System/370 and I/O subsystems used by z/Architecture. Peripheral integration involved vendors such as Adaptec and Racal and was common in installations at corporations including General Electric and Siemens.

Protocol and Communication (3270 Data Stream)

Communication relied on the 3270 data stream protocol, a block-oriented host-to-terminal protocol implemented over coaxial, modified coax, twisted pair, and later Ethernet using 3270 controllers and devices such as TN3270 gateways. The data stream used orders, commands, and buffer addressing to implement forms and protected fields for applications like CICS and IMS, enabling efficient transaction throughput in environments like Wall Street trading floors and government centers. Integration with networking stacks involved standards and products from IBM, Cisco Systems, Microsoft (through TN3270 for Windows), and open-source projects on UNIX systems such as Sun Solaris and Linux.

Emulation and Software Implementations

Emulation implementations include hardware emulators by companies like GTE, Raritan, and software implementations such as tn3270, x3270, s3270, and proprietary clients for Windows from Attachmate and Rocket Software. Emulators provided compatibility layers for modern workstations from Dell, HP, and Apple to access mainframe applications running on z/OS, z/VM, and z/VSE; they also interfaced with middleware from IBM WebSphere, Apache projects, and terminal automation tools used by financial firms like Goldman Sachs.

Use in Mainframe Environments and Applications

3270 terminals were ubiquitous in transaction processing, airline reservation systems such as those run by American Airlines and Sabre, banking applications at JPMorgan Chase and state payroll systems, and in library catalogs at institutions like Library of Congress. Applications included host-based editors, data-entry forms, batch control panels for JCL job streams, and operator consoles on platforms such as OS/2 gateways and VM/CMS consoles. Integration with middleware and transaction managers such as IMS/DC and CICS/TS enabled workloads across industries including finance, healthcare at Mayo Clinic, and retail chains like Walmart.

Legacy and Influence on Modern Systems

The 3270 influenced subsequent terminal standards, the design of terminal emulators, and the development of host-centric application models that persisted into distributed client-server and web architectures, informing technologies used by Microsoft, Oracle Corporation, SAP SE, and cloud providers like Amazon Web Services. Concepts such as screen-oriented forms, field protection, and reduced host I/O overhead are reflected in modern transaction middleware, terminal multiplexer tools, and remote access protocols used by enterprises including IBM, HP, Cisco Systems and government agencies such as Department of Defense. Preservation efforts and museum exhibits by organizations like the Computer History Museum and Smithsonian Institution document 3270’s role in computing history.

Category:Computer terminals