Figure 1. IBM 2703 Transmission Control
The IBM 2703 Transmission Control (Figure 1) ena
bles an IBMSystem/360 to communicate with input/
output devices over a variety of communications
facilities. The2703 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 ofSystem/360 Models 65 and 75 accom
plish the same by using the IBM2870 Multiplexer Channel in conjunction with the 2703. The 2703 is a
multiline communications-control unit that is at
tached to a multiplexer channel of aSystem/360 pro
cessor.
Data-Communication Units
The2703 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 IBM2703 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.
IBM1030 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; or600 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)--at110 bps only. • Teleprinters in World Trade--at 50, .75, or 100 bps. • Another IBM System/360 via an IBM 2701 Data
AdapterUnit (equipped with the appropriate Syn
chronous Features)--at1200 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-
missionControl (equipped with the appropriate
Synchronous Features)--at1200 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)--at1200 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 )-
at1200 bps/150 cps; 2000 bps/250 cps; or 2400 bps/300 cps. *
Attached Communications Lines
The2703 can accommodate from 8 (4 for synchro
nous) to 176 half-duplex lines. Each line reqUires
one nonshared subchannel on the multiplexer channel.
The2703 operates in half-duplex mode with respect
to the messages being communicated.
The2703 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 to600 bps for start/stop communications
(asynchronous), or up to4800 bps for Binary Syn
chronous Communications(BSC). The 2703 can
have as many as 176 lines operating at speeds up to180 bps, 72 lines at 600 bps, 48 lines at 2400 bps,
or 24 lines at4800 bps. Many combinations are
possible; however, the individual system and2703 configuration determine the specific line limitations.
For details on specific com munications facilities,
refer to Appendix B.
In communications with the terminal, the2703 transmits and receives serially by bit and serially by
*Characterrates 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
bles an IBM
output devices over a variety of communications
facilities. The
sing and data communications within the same system
The users of
plish the same by using the IBM
multiline communications-control unit that is at
tached to a multiplexer channel of a
cessor.
Data-Communication Units
The
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
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
to a 2703.
134.5 bps/14. 8 cps; or 75 bps/8. 33 cps.
134.5 bps/14. 8 cps.
134.5 bps/14. 8 cps; or
cps.
at 134.5 bps/14. 8 cps.
minals--at 45.5, 56.89, or 74.2 bps.
56.89, or 74.2 bps.
Type, 8-level code)--at
Adapter
chronous Features)--at
mission
Synchronous Features)--at
Synchronous Data Adapter Feature)--at
Synchronous Communications Adapter feature )-
at
Attached Communications Lines
The
nous) to 176 half-duplex lines. Each line reqUires
one nonshared subchannel on the multiplexer channel.
The
to the messages being communicated.
The
code, and speed. A basic unit may have as few as
eight lines (four for synchronous) and operate at
speeds up to
(asynchronous), or up to
chronous Communications
have as many as 176 lines operating at speeds up to
or 24 lines at
possible; however, the individual system and
For details on specific com munications facilities,
refer to Appendix B.
In communications with the terminal, the
*Character
transmission code. Higher character rates are achieved with Six
Bit Transcode. Six-Bit Transcode cannot be used with 4800 bps.
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