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• Faster transmission speed to and from the
buffer.
• A reduction in manual entry.
• Visual verification before transmission.
• Clean copy output (with Buffered Receive fea
ture installed).
• Ease in correction of keying erro rs.
• Automatic retransm ission, if Record Checking
feature is installed.
• Flexibility in selection of communication facili
ties.
COMMUNICATIONS FACILITIES
The IBM 2740 Model 2 is designed for communicating
with an IBM System/360 Model 25, 30, 40, 50, 65,
75, or 85 through an IBM 2701 Data Adapter Unit,
an IBM 2702 or 2703 Transmission Control Unit, or
an IBM 2712 Remote Multiplexer over privately
owned or leased com m on-carrier facilities.
Model 2 operates in a half-duplex mode only over:
• Common-carrier leased private-line telephone
service.
• Common-carrier leased private-line telegraph
service:
Telephone Company Type 1006 (150 Baud) chan
nels
Telephone Company Type 1005 (7 5 Baud)* Chan
nels
Western Union Class C (75 Baud)* Channels.
• Western Union Class D (180 Baud) Channels.
• Western Union Class E Channels, or
• Equivalent privately owned communications faci
lities .
♦Telegraph Line Adapter (IBM special feature) is required. The
channel must be capable of operating at 75 bps (bits per second)
w ith the 9 -b it-p e r-ch a ra cte r code, and must be term in ated in
a 6 2 .5 -m a neutral dc loop a t the term in al. N on-code-sensitive
regenerators must also be used on the channel.
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Data Sets
The IBM 2740 Model 2 operates over communication
facilities using the following data sets or their equiva
lent:
• Western Electric Data Set 103F2—for use in
multipoint or point-to-point leased private line
telephone service.
• Western E lectric Data Set 202D1—for use in
multipoint or point-to-point leased private-line
telephone service (4-wire facilities only).
• IBM Line Adapters (Limited Distance Type 1,
Limited Distance Type 2, Leased Line, and
Shared Line)—for use in multi-terminal or point-
to-point operations on privately-owned line con
nections or com m on-carrier leased private con
nections. Refer to the Special Features, Model
2 section for further information.
• An appropriate channel termination for use on
Telephone Company 150 baud (Schedule 1006)
channels.
The
• Western Union Data Loop Transceiver 1183-A for
use on Western Union Class D (180 baud) channels.
Line-Control Signals
The line-control signals used for the 2740 Model 2
are identical to those used for the 2740 Model 1
(See Line-Control Signals in the 2740 Model 1 section
of this manual).
MODES OF OPERATION
The IBM 2740 Model 2 can operate in either local
or communicate mode.
Local Mode
In local mode, the terminal will be in one of three
status conditions:
Enter. Keyboard-entered data will be loaded into
the buffer as well as printed.
Print Back. The contents of the buffer will print
out with each operation of the Bid key.
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