IBM 2712
Remote
Multiplexer
Model 1
2 Full duplex • voi ce-grade • • • • Communication • Channel 10 Figure 9. Typical 2712 Configuration
TERMINAL CONTROL OPERATIONS The 2703 operates with the following terminal
controls:
IBM Terminal Control Type I
IBM Terminal Control Type II
Telegraph Terminal Control Type I
Telegraph Terminal Control Type II
At least one such feature is required; a maximum
of four start/stop terminal-control features is
possible for anyone 2703. IBM Terminal Control Type I
This feature provides controls necessary for the
attachment of 2740, 2741, 1050, 1060, and 1070 terminals at 14.8 cps (134.5 bps); 1070 terminals
at 66.6 cps (600 bps); or 1050 terminals (with the
Telegraph Attachment feature) at 75.0 bps. The
transmission code is six bits plus parity, with the
following relation to the System/360 channel inter­
face:
o 2 3 4 5 6 7 System/360 Byte Shift • S B A 8 4 2
Check Six-Bit BCD IBM 2703 Transmission Control
2
2712 Model 1
Adapter 3
Feature • 2712
Multiplexer
Line
Channel • To
Adapters II CPU 8
2712 Model 1
9
Expander
Feature 10 In the six-bit BCD transmission code, ® represents
the shift bit. A logical one identifies the upper case;
a logical zero represents the lower case. The @ bit is the first bit transmitted after the start bit.
An odd-parity (check) bit is transmitted following the
1 bit. Each received character i's checked for odd
vertical parity.
Shifted-character-set conversion, a standard
feature, automatically deletes the upshift and down­
shift characters from the received data stream,
notes the last shift character received, and inserts
an eighth bit, ® , to indicate the appropriate shift
character to the System/360. On outgoing data, the <ID (shift) bit is removed and noted. A change in this ® bit automatically causes insertion of the appro­
pritate shift character (upshift or downshift) into the
outgoing data stream before sending the data
character. Start B A 8 4 2 Ch;f< 1 C
{
Outgoing Data Stop Character
The © (check) bit in the character indicates the
correct odd-parity count: a logical one if the bit
39

... 712 Adapter 2
M E odels with
_xponder feature 0 1
expander ') .. expander [ )( w "'0 C o N 3
expander
4
expander 0 0 8
14
?? I I 28 I 36 -+2 50 56
Model 1 ana Expander Feature
1 expander 2 expander 3 expander
8 10 18 20 28 30 16 18 26 28 36 I 38
22 24 32 34 42 44 3? 4f) 42 - - I I 36 38 46 48
44 46 50 52
Figure 10. Total Low-Speed Lines Available by 2712 Model Configurations 40 4 expander
38 40 Note:
l. The total low s available for a
peed line terminations
ny given 2712
configuration is determined by the
the Modell and
nates. A" i ndi cated
cumulative, thus the
intersection of
Model 2 coordi
features are ac
second model 1 adapter feature
assumes prior attachment of the first
model I teature with the hrst expander
feature, etc.
2. The Expander features require a block
of eight addresses, while providing
two line terminations for the Model I, or six line terminations for the
Model 2.