Figure 1. IBM 2703 Transmission Control
The IBM 2703 Transmission Control (Figure 1) ena­
bles an IBM System/360 to communicate with input/
output devices over a variety of communications
facilities. The 2703 permits users of System/360 Models 25,30,40, and 50 to combine data proces-
sing and data communications within the same system
The users of System/360 Models 65 and 75 accom­
plish the same by using the IBM 2870 Multiplexer Channel in conjunction with the 2703. The 2703 is a
multiline communications-control unit that is at­
tached to a multiplexer channel of a System/360 pro­
cessor.
Data-Communication Units
The 2703 directs and controls information flow be­
tween the system and a variety of remote communi­
cations terminals over leased common-carrier
private-line facilities, common-carrier switched
facilities, or equivalent privately owned communica­
tions facilities. Data-communication equipment that
can be connected to the IBM 2703 is included in the
following listing, and is illustrated by Figure 2. The
operating speeds available are indicated in bits per
second (bps) and usually also in characters per sec­
ond (cps). IBM 2711 Line Adapter Unit. IBM 2712 Remote Multiplexer.
IBM 1030 Data Collection System--at 600 bps/ 60 cps; or 600 bps/14. 8 cps. NOTE: The IBM 1032 Digital Time Unit cannot be attached
to a 2703. IBM 1050 Data Communication System--at
134.5 bps/14. 8 cps; or 75 bps/8. 33 cps. IBM 1060 Data Communication System--at
134.5 bps/14. 8 cps. IBM 1070 Process Communication System--at
134.5 bps/14. 8 cps; or 600 bps/66. 6 or 13.3
cps. IBM 2740 or 2741 Communications Te:rminal-­
at 134.5 bps/14. 8 cps. AT&T 83B2/83B3 Type Selective Calling Ter­
minals--at 45.5, 56.89, or 74.2 bps. Western Union Plan 115A Terminals--at 45.5,
56.89, or 74.2 bps. Common-Carrier TWX Stations (Model 33/35
Type, 8-level code)--at 110 bps only. Teleprinters in World Trade--at 50, .75, or 100 bps. Another IBM System/360 via an IBM 2701 Data
Adapter Unit (equipped with the appropriate Syn­
chronous Features)--at 1200 bps/150 cps; 2000 INTRODUCTION bps/250 cps; 2400 bps/300 cps; or 4800 bps/ 600 cps. * Another IBM System/360 via an IBM 2703 Trans-
mission Control (equipped with the appropriate
Synchronous Features)--at 1200 bps/150 cps; 2000 bps/250 cps; 2400 bps/300 cps; or 4800 bps/600 cps. * IBM System/360 Model 20 (equipped with the BSC Adapter Feature)--at 1200 bps/150 cps; 2000 bps/250 cps; 2400 bps/300 cps; or 4800 bps/600 cps. IBM System/360 Model 25 (equipped with the
Synchronous Data Adapter Feature)--at 1200 bps/150 cps; 2000 bps/250 cps; 2400 bps/300 cps; or 4800 bps/600 cps. IBM 2780 Data Transmission Terminal--at 1200 bps/150 cps; 2000 bps/250 cps; or 2400 bps/300 cps. * IBM 1130 Computing System (equipped with the
Synchronous Communications Adapter feature )-­
at 1200 bps/150 cps; 2000 bps/250 cps; or 2400 bps/300 cps. *
Attached Communications Lines
The 2703 can accommodate from 8 (4 for synchro­
nous) to 176 half-duplex lines. Each line reqUires
one nonshared subchannel on the multiplexer channel.
The 2703 operates in half-duplex mode with respect
to the messages being communicated.
The 2703 is flexible in line capacity, transmission
code, and speed. A basic unit may have as few as
eight lines (four for synchronous) and operate at
speeds up to 600 bps for start/stop communications
(asynchronous), or up to 4800 bps for Binary Syn­
chronous Communications (BSC). The 2703 can
have as many as 176 lines operating at speeds up to 180 bps, 72 lines at 600 bps, 48 lines at 2400 bps,
or 24 lines at 4800 bps. Many combinations are
possible; however, the individual system and 2703 configuration determine the specific line limitations.
For details on specific com munications facilities,
refer to Appendix B.
In communications with the terminal, the 2703 transmits and receives serially by bit and serially by
*Character rates are based on the use of USASCII or EBCDIC as the
transmission code. Higher character rates are achieved with Six­
Bit Transcode. Six-Bit Transcode cannot be used with 4800 bps.
5
Previous Page Next Page