270x is a generic name for a family of IBM non-programmable communications controllers used with System/360 and

System/370 The IBM System/370 (S/370) is a model range of IBM mainframe computers announced on June 30, 1970, as the successors to the System/360 family. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path ...

computers. The family consisted of the following devices: * IBM 2701 Data Adapter Unit * IBM 2702 Transmission Control * IBM 2703 Transmission Control The 2701 and 2702 were announced simultaneously with System/360 in 1964, the 2703 was announced a year later. The 270x series was superseded by the IBM 3704 and 3705 communications controllers in 1972.

2701

The 2701 supported up to four start-stop or synchronous communications lines. It had two multiplexor channel interfaces for connection to one or two host computers. The synchronous adapter originally supported the ''Synchronous Transmit-Receive (STR)'' protocol, and later ''Binary Synchronous Communications (BISYNC)'' when it was introduced in 1967, in

half duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

mode at speeds of up to 40,800 bits per second (bit/s). The 2701 could also have "data acquisition and control adapters" for direct control of external equipment. Initially the 2701 supported the following devices: *

IBM 1009 The IBM 1009 Data Transmission Unit was an IBM communications controller introduced in 1960. The 1009 used the Synchronous transmit-receive (STR) protocol to transfer data at 150 characters per second (cps) over a single point-to-point dial or le ...

Data Transmission Unit *

IBM 1013 The IBM 1013 Card Transmission Terminal was a device manufactured by IBM from 1961 which transmitted the data held on 80-column cards to a remote computer or another 1013. The speed was generally considered 100 cards per minute but could be f ...

Card Transmission Terminal *

IBM 7701 The IBM 7701 Magnetic Tape Transmission Terminal was a communications device announced by IBM in 1960. It was designed to transfer the contents of a reel of magnetic tape over a leased or dial telephone circuit. The IBM 7702 was a similar device ...

Magnetic Tape Transmission Terminal *

IBM 7702 The IBM 7701 Magnetic Tape Transmission Terminal was a communications device announced by IBM in 1960. It was designed to transfer the contents of a reel of magnetic tape over a leased or dial telephone circuit. The IBM 7702 was a similar device ...

Magnetic Tape Transmission Terminal * IBM 7710 Data Communication Unit * IBM 7711 Data Communication Unit * IBM 7740 Communication Control System * IBM 7750 Programmed Transmission Control * Remote System/360 with 2701 * Serial synchronous terminals *

IBM 1030 The IBM 1030 Data Collection System was a remote terminal system created by IBM in Endicott, New York in 1963, intended to transmit data from remote locations to a central computer system. Description The system consisted of the following compone ...

Data Collection System *

IBM 1050 IBM 1050 Data Communications System is a computer terminal subsystem to send data to and receive data from another 1050 subsystem or IBM computer in the IBM 1400, IBM 7000 or System/360 series. It first became available in 1963 and was used wi ...

Data Communication System * IBM 1060 Data Communication System *

IBM 1070 IBM 1070 Process Communication System was IBM's communication system with analog-to-digital and digital-to-analog conversion functions that was announced in 1964 for the process industries (oil refinery, iron & steel, pharmaceutical and other indu ...

Process Communication System * AT&T 83B2 Type Selective Calling Terminals * Western Union Plan 115A Outstations * Common Carrier TWX Stations * European Teleprinters * Parallel data devices * Contact sense terminals * Contact operate terminals Later the

IBM 2740 The IBM 2741 is a printing computer terminal that was introduced in 1965. Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter op ...

and

IBM 2741 The IBM 2741 is a printing computer terminal that was introduced in 1965. Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter op ...

Communication Terminals, and the IBM 2260/2848 were added.

2702

The 2702 could accommodate up to 31 communication lines, but at a slower speed than the 2701. The System/360 Configurator indicates that in the 2702 supported start-stop lines only. Initially the 2702 supported the following terminals: *

Data Collection System *

Data Communication System * IBM 1060 Data Communication System *

Process Communication System * AT&T 83B2 Type Selective Calling Terminals * Western Union Plan 115A Outstations * Common Carrier TWX Stations * European Teleprinters Later the

and

Communication Terminals, the IBM 1032 Digital Time Unit, and a second channel interface were added.

2703

The 2703 supported up to 176 half-duplex start-stop or Binary Synchronous communication lines. The maximum speed of one line was 2400 bit/s but the total aggregate line speed was limited. By 1970 the maximum line speed had been raised to 4800 bit/s. The 2703 attached to a single multiplexer channel; each communication line occupied a subchannel. It had a four or eight byte buffer per line to reduce data transfer to and from the host computer. The IBM 2712 Remote Multiplexer allowed up to fourteen slow speed devices to be multiplexed over one high speed line to a 2703. As of 1967 the 2703 supported the following devices: *

Data Collection System *

Data Communication System * IBM 1060 Data Communication System *

Process Communication System *

and 2740 Communications Terminals * AT&T 83B2 Type Selective Calling Terminals * Western Union Plan 115A Outstations * Common Carrier TWX Stations * Remote System/360 via 2701 with 2701 or 2703 *

IBM 2780 The IBM 2780 and the IBM 3780 are devices developed by IBM to perform remote job entry (RJE) and other batch functions over telephone lines; they communicate with the mainframe via Binary Synchronous Communications (BSC or Bisync) and replaced o ...

Data Transmission Terminal *

IBM 1130 The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding th ...

Computing System with Synchronous Communications Adapter (SCA)

Clones

Many companies produced clones of 270x controllers, such as the

Memorex Memorex Corp. began as a computer tape producer and expanded to become both a consumer media supplier and a major IBM plug compatible peripheral supplier. It was broken up and ceased to exist after 1996 other than as a consumer electronics bran ...

1270, introduced in 1970, and devices from NCR-Comten.

References

{{Reflist

External links

Component Description: IBM 2701 Data Adapter Unit

IBM 2703 Transmission Control Component Description

270x 270x is a generic name for a family of IBM non-programmable communications controllers used with System/360 and System/370 computers. The family consisted of the following devices: * IBM 2701 Data Adapter Unit * IBM 2702 Transmission Control * I ...