See Note 113 To Terminals
via Data Sets or Line
Adapters
r-----, I Line Set Ill-I See Note 112 Line
Base I Line I r-----, I Terminal I See Note #1 To Terminals
via Data Sets or Line ----, Base --L __ --1 Common
Controls and
Storage
Adapters See Note 114 D -----r - Line I I Base ---L __ --1 t:l2W: 8 'I-Termina! Controls-Max. of 6 per 2703. *2 Line Bases*-Max. of 3 per 2703. '3 Line Sets**-Per Line Base a",J Per 2703. Table 1 under Line Sets ',n Start/Stop Special Features gives detailed information.
#4-Lines per Line Set-Max. of 8***per sis line set.
Max. of 4 per Sync. line set.
Legend:
S/S-Start/Stop type operations
Sync. -Synchronous type operations
*-Check Figure 8 for various line base configurations.
**-These maximums are influenced by the Feature linitations Per 2703, described
in the Special Features Summary.
***-Except where this is increased to 16 lines by an expander feature.
Refer to the 2712 Modell and Model 2 Adapter Features for details of how the 2712
expander features increase the number of available lines.
Figure 3. 2703-Internal Organization P 0 2 3 4 5 6 7-Bits
To Multiplexer
Channel Connection , I

word (MDW-l, 2) in the common-controls-and­
storage section. When four bytes are accumulated,
they are transferred to the multiplexer channel via
the riO-interface controls.
Terminal Controls
This section performs functions associated with a
particular type of terminal equipment. The terminal­
controls section acts as the extension of common con­
trols, performing such unique duties as: determin­
ing character bit length, character-sequence recog­
nition, shift-character recognition, pad-character
control, and initiating LRC checking. A terminal
control is assigned by line set, and all lines con­
nected to a specific line set must be of the same ter­
minal type. The addressing circuit that selects the
line also selects the associated delay-line storage
(base control word--delay-line type storage), MCW,
and terminal control.
Line Bases
The line-base section performs bit sampling while
accepting bits directly from the line adapters during
a receive operation. It buffers and time-multiplexes
the data before sending the bits (characters, for syn­
chronous operations) to the common-controls-and­
storage section. The reverse procedure takes place
during a transmit operation. A base-control word in
the delay line of the line base is used for bit buffer­
ing (character buffering, for synchronous operations)
and bit sample control. The line base is limited to a
certain number of lines, depending on the type of base.
Line Sets The line sets interface the communications facilities
(lines) to the 2703 and provide bit buffering for the
Transmit Data line. At least one line set must be
selected for 2703 operation. Each line set consists
of eight line adapters (four, for synchronous), with
each adapter servicing one communications line.
IBM 2711 Adapter Unit This is a free-standing unit that provides housing and
power for up to 32 IBM Line Adapters (Shared-Line,
Leased-Line, and Limited-Distance Type 2--eight
miles). These line adapters interface with the 2703 via the Data Line Set special feature, with one
line set required for each eight lines. The 2711 may
be attached on a per-line basis to more than one 2703. Any combination of line adapters up to 32 can be
accommodated by the 2711.
IBM 2712 Remote Multiplexer
The 2712 consists of a free-standing unit at the re­
mote communications point and several special fea­
tures available for adding to the 2703. These 2703 features allow up to 10 lines oJ:"'rating at 134.5 bps
or 14 lines operating at 74.2 bps to be bit-multiplexed
onto one voice-grade line. Refer to "2712 Modell
and Model 2 Adapter Features" under "Start/Stop Special Features" for further details.
9