IBM 270x
| Company type | Product line |
|---|---|
| Industry | Computer hardware |
| Founded | 1964 |
| Successor | IBM 3704 and 3705 communications controllers |
| Products | IBM 2701 Data Adapter Unit, IBM 2702 Transmission Control, IBM 2703 Transmission Control |
| Parent | IBM |
270x denotes a series of IBM communication controllers without programmability, created for use with System/360 and System/370 mainframe computers.
This lineup comprised:
- IBM 2701 Data Adapter Unit
- IBM 2702 Transmission Control
- IBM 2703 Transmission Control
The IBM 2701 and 2702 debuted concurrently with the System/360 in 1964, while the 2703 was introduced a year later in 1965. In 1972, this family was succeeded by the IBM 3704 and 3705 communications controllers.
2701
The IBM 2701 was capable of managing up to four communication lines, either start-stop or synchronous, and incorporated two multiplexor channel interfaces to connect with one or two host systems. Initially supporting the Synchronous Transmit-Receive (STR) protocol, it expanded its capabilities in 1967 to include Binary Synchronous Communications (BISYNC), functioning in half-duplex mode at speeds reaching 40,800 bits per second. Additionally, it provided adapters for data acquisition and external control applications.
Devices originally compatible with the 2701 included:
- IBM 1009 Data Transmission Unit
- IBM 1013 Card Transmission Terminal
- IBM 7701 and 7702 Magnetic Tape Transmission Terminals
- IBM 7710 and 7711 Data Communication Units
- IBM 7740 Communication Control System
- IBM 7750 Programmed Transmission Control
- Remote System/360 utilizing the 2701
- Serial synchronous terminals
- IBM 1030, 1050, 1060, and 1070 Data Communication Systems
- AT&T 83B2 Selective Calling Terminals
- Western Union Plan 115A Outstations
- Common Carrier TWX Stations
- European Teleprinters
- Parallel data devices and contact terminals
Subsequent additions to supported hardware encompassed the IBM 2740 and 2741 Communication Terminals, alongside the IBM 2260/2848 display terminals.
2702
Designed to manage up to thirty-one communication lines at slower rates than the 2701, the IBM 2702 exclusively supported start-stop line types. Initially, it interfaced with terminals such as the IBM 1030, 1050, 1060, and 1070 series; AT&T 83B2 Selective Calling Terminals; Western Union Plan 115A Outstations; Common Carrier TWX Stations; and European Teleprinters. Later enhancements incorporated support for the IBM 2740 and 2741 Communication Terminals, the IBM 1032 Digital Time Unit, as well as adding a second channel interface.
2703
The IBM 2703 was engineered to handle up to one hundred seventy-six half-duplex communication lines using start-stop or Binary Synchronous protocols. Initially limited to line speeds of up to 2400 bits per second, this was increased to a maximum of 4800 bits per second by around 1970. The controller connected through a single multiplexer channel, allocating individual subchannels per line and employing buffers of four or eight bytes each to enhance data throughput. The IBM 2712 Remote Multiplexer allowed for multiplexing as many as fourteen slower devices over one high-speed line linked to the 2703.
By the year 1967, compatible equipment included the IBM 1030, 1050, 1060, and 1070 systems; IBM’s own 2741 and 2740 terminals; AT&T’s 83B2 terminals; Western Union Plan 115A Outstations; Common Carrier TWX Stations; Remote System/360 connections via either the 2701 or the 2703; IBM’s 2780 Data Transmission Terminal; and the IBM 1130 Computing System equipped with a Synchronous Communications Adapter (SCA).
Clones
A number of manufacturers developed clones of the IBM 270x controllers. Among these was Memorex with its introduction of the Memorex 1270 in 1970, alongside other models produced by NCR-Comten.