Ignore Mode . 2·13; Terminal Mode - IBM 5100 Maintenance Information Manual

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The function of each EIA line and the sequence in which
they are turned or sensed during serial I/O operations in
modem mode is:
• After the serial I/O program is loaded and enabled, the
5100 turns on '+SIO data term rdy', which is sensed on
the data set ready line at the I/O device, to indicate
that the 5100 is ready for serial I/O operations.
• The serial I/O device turns on data terminal ready,
which is sensed on the '+SIO data set rdy' line on the
expansion feature card, to indicate that the serial I/O
device is ready for serial I/O operations.
Note: The sequence in which data terminal ready and data
set ready are activated is not significant.
When the serial I/O device is going to transmit data to the
5100:
1. The serial I/O device turns on the request to send
line, which is sensed at the '+SIO clear to send'
line on the expansion feature card, to indicate that it
is ready to send data.
2. The 5100 then turns on the '+SIO request to send'
line, which is sensed on the clear to send line at the
I/O device, to indicate that it is ready to receive the
data from the I/O device.
3.
The serial I/O device sends the data on the transmitted
data line, which is received on the '+SIO rcvd data'
line at the expansion feature card.
When the serial I/O device is going to receive data from the
5100:
1. The lines data terminal ready and data set ready are
activated the same as when the I/O device is trans-
mitting data to the 5100.
2.
3.
The line request to send from the I/O device ('+SIO
clear to send' at the expansion feature card) must
be off. Therefore, the line '+SIO request to send'
at the card (clear to send at the I/O device) will also
be off.
The 5100 sends the data on the '+SIO xmit data'
line and the data is received on the received data line
at the I/O device.
The received line signal detector line is active when the
'+SIO data term rdy' line is active and is provided for
I/O devices that require this signal.
Ignore Mode
In ignore mode, the sequence and function of the lines
are the same as they are in modem mode. (See Modem
Mode.) However, when the I/O device is going to send data
to the 5100, the 5100 turns on the '+SIO request to send'
(clear to send line at the I/O device) without checking the
request to send line from the I/O device ('+SIO clear to
send' at the expansion feature card).
When the serial I/O device is going to receive data from the
5100, the line '+SIO request to send' (clear to send at the
I/O device) remains off.
Terminal Mode
A flip cable (terminal cable) is used in terminal mode to
connect the serial I/O device to the serial I/O connector.
In this cable the following lines are interchanged:
Data terminal ready and data set ready
Request to send and clear to send
Transmitted data and received data
Therefore, the line names at the serial I/O device conform
to the line names at the expansion feature card.
Theory Of Operation 2-13