Common-Carrier TWX Stations (Model 33/35
Teletypewriter terminals) using 8-level code.
World Trade Telegraph Terminal Control A maximum of one per 2703 is permitted. This
feature allows for the attae hment of: World Trade teleprinters.
IBM Terminal Control Base
A maximum of one per 2703 is permitted. An IBM
Terminal Control Base must be specified for the 2703 if the user wishes to include either IBM
Terminal Control Type I, or IBM Terminal Control Type II, or both.
Telegraph Terminal Control Base
A maximum of one per 2703 is permitted. A Tele­
graph Terminal Control Base must be specified for
the 2703 if the user wishes to include Telegraph
Terminal Control Type I, Telegraph Terminal Con­ trol Type IT, or World Trade Telegraph Terminal Control. Line Bases
A Start/Stop Line Base Type I accommodates up to
88 half-duplex lines operating at speeds up to 180 bps;
a Start/Stop Line Base Type II accommodates up to
24 half-duplex lines at speeds up to 600 bps.
A maximum of three line bases may be attached
to any 2703. However, a limitation of 176 lines per 2703 means that if three Type I bases are installed,
only 176 lines can be attached for the three bases.
The possible combinations available are shown in
Figure 8.
Base Expansion Feature
This feature is required if more than one Start/ Stop Base Type I or II is to be installed in the 2703. It is also required whenever a Syr:chronous Attach­
ment is specified. A maximum of one Base Expan­
sion feature per 2703 is permitted.
Line Sets Seven types of start/stop line sets are available.
Also, nine speed options are available tor start/
stop. The choice of line set is generally independent
of the' type of terminal but dependent on the communi­
cations facilitr specified. All lines in a given line __ __ \'- I!-" t, facilities. Table I summarizes the line sets per line
base and per 2703. The line sets av'ailable are as
follows.
Data Line Set A maximum of twelve per 2703 is permitted. This
feature provides the line terminations for connecting
to eight common-carrier-supplied data sets per
feature. The following data sets (or equivalent) can
be attached via this line set:
IBM 2711 Line Adapter Unit Western Electric 103A1 and 103A2 Western Electric 103F2 Western Electric 202D1 and 202D2 Western Union 1183A
Data Line Set Expander
This feature provides for eight additional half-
duplex line terminations as an expansion of the Data
Line Set feature. Each expander is associated with
the basic Data Line Set feature on a one-to-one basis,
up to a maximum <:f 10 per 2703. IBM Line Set 1A
This feature provides the line terminations for a
attachment to eight half-duplex privately owned lines
via IBM Limited-Distance Line Adapter Type IA
(two-wire IBM modem for distances up to 4.75
miles). It accommodates IBM 2740/2741 Communi­ cation Terminals. Maximum total of this feature and
mM Line Set 1B features cannot exceed twelve. This
feature cannot be installed if any IBM Line Set 2 is
installed.
mM Line Set 1B
This feature provides the line terminations for
attachment to eight half-duplex privately owned lines
via IBM Limited-Distance Line Adapter Type m
(four-wire mM modem for distances up to 4. 75
miles). It accommodates mM 2740/2741 Communi­ cation Terminals. Maximum total of this feature and IBl'vl Line Set lA features cannot exceed twelve. This feature cannot be installed if any IBM Line Set 2 is installed.
mM Line Set 2
This feature provides the line terminations for
attachment to eight IBAI Limited-Distance Line Tq)(' II (D.H)-\\'i re IBl\I mode 111 tor riistances 'In tu ,-" nllll',",). It alT\)[lllIlULialL.c. lL •. \l -,U. 1')".', j!Ii.(I 1 Ij'i() , alld 2';""::0 1:":7-11 Systt'lliS and termin::tb, I

Maximum number of features per 2703 is four. This
feature cannot be installed if any mM Line Set lA or
1B features are installed.
Telegraph Line Set This feature provides the line terminations for eight
half-duplex telegraph lines. A maximum of twelve
of these features are permitted on anyone 2703. Telegraph Line Set Expander
This feature provides for eight additional half-duplex
line terminations as an expansion of the Telegraph
Line Set feature. Each expander feature is associatec
with the basic Telegraph Line Set feature on a one to
one basis, up to a maximum of ten per 2703. World Trade Telegraph Single-Current Line Set This feature provides the line termination for eight
simplex or half-duplex single-current telegraph lines
operating at 50 or 75 bps. Two simplex connections
can be used as one full-duplex connection for a maxi­
mum of four full-duplex lines per line set. The
maximum number of line sets is six per start-stop
Base and 12 per 2703. World Trade Telegraph Single-Current Line Set Expander
This feature provides an additional eight simplex or
half-duplex single-current telegraph lines per line se
The maximum number of line set expanders are: One per line set.
Five per Start-Stop Base.
Ten per 2703. World Trade Telegraph Double-Current Line Set This feature provides the attachment of up to eight
simplex or half-duplex double-current telegraph lines
operating at 50, 75, or 100 bps via the IBM 3945
Model 11 Telegraph Line Termination (serial #200 or
above). Two simplex connections can be used as one
full-duplex connection for a maximum of four full­
duplex lines per line set. The maximum number of
this feature is six per Start-Stop Base and 12 per 2703. The 2703 provides power for a limited number of IBM
3945 Model 11 'So When the number of 3945's exceed
this limit, the IBM 3945 Additional Power Supply Feature #2822 must be installed to power the extra
units. The maximum number of 3945 Model 11 's that
can be powered by each 2703 Start-Stop Base is
dependent of the mixture of single-current and double­
current line sets. The number of 3945's that can be
powered by each base is:
No. of Single- No. of 2703 Current Line Sets powered 3945's
1 4
2-5 3
6 or more 2
World Trade Telegraph Double-Current Line Set Expander
This feature provides an additional eight simplex or
half-duplex double-current telegraph lines per line
set. The maximum number of line set expanders are: One per line set.
Fi ve per Start-Stop Base.
Ten per 2703. Line-Speed Options
These speed options provide nine spe,cific operating
speeds from 45.5 bps to 600 bps to accommodate the
wide range of start/stop type terminals attachable
to the IBM 2703. Anyone line-speed option of a given
36.1