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2. Press the home-reader start button to cause:
a. Tape reader to read from the master tape:
Prefix, one-Printer 1 on,
CR/LF-Restore the print element to the left
margin and line space vertically,
Prefix, seven-Punch 1 off. This prefix seven code
is a precautionary code placed in this position to
ensure that an extra EOB is not punched into the
tape at this point. When the tape is spliced, the
tape reader starts to reread the
START
portion of
the tape before the previous card is ejected and
a new one is fed and read.
Prefix, zero-Reader 2 on, Reader 1 off (transfers
reading to the card reader from the tape reader).
This code is used as a means of conh·olling the
number of cards packed per line.
b. Card reader to read from the card:
Columns 1-2 contain the prefix three code to
turn the tape punch on.
Columns 3-22 contain data to be packed.
Columns 23-24 contain the prefix nine code which
transfers reading to the tape reader from the card
reader.
c. Tape reader to read from the master tape:
Prefix seven code which turns off the tape punch
prior to returning to the card to read EOB. This
prevents the tape punch from placing an EOB
code in the tape following the data from each
card. Therefore, it is possible to pack several
cards into one line of data with one EOB per line.
Prefix zero code transfers reading to the card
reader from the tape reader.
d. Card reader to read from the card:
Column 25 contains an EOB code which causes
the card to eject and a new card to feed and read
(repeat steps b, c and d).
This operation continues until the fourth transfer to
the tape reader. At this time the EOB in the master
tape is read and punched. This is followed by the read-
ing and execution of the CR/LF code. The reading of
cards and the punching of data into tape then con-
tinues for the second packed line.
Point-to-Point Operation (Figure 33)
When only two terminals are connected to a communi-
cations line, the operation is termed point-to-point. All
1050 Systems connected to public telephone, or leased-
line switched networks, operate point-to-point. This is
64
1050 Detailed Information
distinguished from multipoint networks on leased or
private non-switched lines. Possible modes of operation
for point-to-point communication are:
Master
1.
or
2.
3.
4.
5.
Transmission
Control
Unit
Transmission
Control
Unit
Master
or
Transmission
Control
Unit
1051
Line Control
Off
1051
Line Control
Off
no voice
1051
103-F, Telegraph Attachment,
Line Control
Line Adapter
On
voice
1051
-I
Line Control
103-A
Off
voice
~
1051
Line Control
103-A
On
voice or no voice
1051
103-A, 103-F, Telegraph
Line Control
Attachment,
On
Line Adapter
voice or no voice
1051
103-A, 103-F, Telegraph
Line Control
Attachment,
Off
Line Adapter
In
Examples 1-3, either the master station or the
transmission control unit always controls the line and
thus, the message traffic. In Example 4, the terminal
operating with line control off can not recognize polling
or addressing responses. When addressing therefore,
time must be allowed to receive a response before
transmitting the text. When polling, the transmis-·
sion of text from the polled terminal must be delayed
until the polling terminal transmit time-out (9-18 sec-·
onds) has ended. However, the waiting period at the
polled terminal can be reduced by pressing the resend
button at the polling terminal after the polling address
is sent (this resets the transmit time-out).
In
Example 5, a contention system exists, especially
with a no voice-line connection.
In
this case, the ter-
minal which transmits the first character, controls the
line. The receiving terminal cannot transmit until the
end of its 9-18 second receive time-out. The only indi-
cation to the operator as to when this occurs is the lack
of further text reception, or trying to send by keying
or starting a reader.
For both Examples 4 and 5, receive units should al-
ways be assigned to line and ready, to ensure that all
transmissions are received. With line control off, there
is no way to determine at the sending terminal if the
receive units are ready to receive data.
Unattended operation is possible in any of the point-
to-point examples described (1-5), as well as in multi-
point operations. For maximum efficiency in such op-
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