IBM RT Series Hardware Reference Manual page 81

Modem Control Register
This 8-bit register controls the interface with the modem or data set (or other peripheral device).
The contents of the modem control register are described below:
Mode~
Control RegIster
(Hex Address n234, n23C, n244 )
Bit 7 6 5 4 3 2
a
Data terminal ready
Request to send
OUT1
~--------~~~
OUT2
~------------~~~
LOOP
L-------------tl~~
=
a
L.....-----------tl~~ =
a
"'---------------------------e-~
=
a
Bit 0 This bit controls the data terminal ready (-DTR) output. When bit 0 is set to a logical
1, the -DTR output is forced to a logical O. When bit 0 is reset to a logical 0, the -DTR
output is forced to a logical 1.
Note: The -DTR output of the NS16450 may be applied to an EIA inverting line
driver to obtain the proper polarity input at the modem or data set.
Bit 1 This bit controls the request to send (-RTS) output. Bit 1 affects the -RTS output in a
manner identical to that described above for bit O.
Note: The -RTS output of the NS16450 may be applied to an EIA-inverting line
driver to obtain the proper polarity input at the modem or data set.
Bit 2 This bit controls the output 1 (-OUT 1) signal, which is an auxiliary user-designated
output. Bit 2 affects the -OUT 1 output in a manner identical to that described above
for bit O.
Note: The -OUT 1 output of the NS 16450 may be applied to an EIA inverting line
driver to obtain the proper polarity input at the modem or data set.
Bit 3 This bit controls the output 2 (-OUT 2) signal, which is an auxiliary user-designated
output. Bit 3 affects the -OUT 2 output in a manner identical to that described above
for bit O.
Note: The -OUT 2 output of the NS 16450 may be applied to an EIA inverting line
driver to obtain the proper polarity input at the modem or data set.
5080 Peripheral Adapter
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