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Full Discussion: Serial Lines Explained
Top Forums UNIX for Dummies Questions & Answers Serial Lines Explained Post 302930455 by sreyan32 on Sunday 4th of January 2015 11:15:36 AM
Old 01-04-2015
Okay from what I have read in this thread I can understand that in the older days you would have a monitor and a keyboard with a serial port connecting to the central CPU. You would communicate with the CPU using signals sent via the serial port. I know this is an over simplification but is it correct ?

Can someone explain how serial ports can be used for session control in a little more detail ?

What baffles me is that is why still use serial ports ? Why not remove them ? On a normal desktop or laptop serial ports are not used the way they were used back in the olden days, so keep them ?

For example as Corona688 mentioned in a earlier thread
stty still gives the baud rate. This is not required so why still keep it.

Why adopt an old standard forcefully when it is not required is my point
 

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LEARN ABOUT ULTRIX

mdc

mdc(4)							     Kernel Interfaces Manual							    mdc(4)

Name
       mdc - DS5100 serial line driver

Syntax
       device	 mdc0	  at ibus?     vector mdcintr
       device	 mdc1	  at ibus?     vector mdcintr
       device	 mdc2	  at ibus?     vector mdcintr

Description
       A  DS5100 base system (mdc0) provides four asynchronous ports.  An optional asynchronous card (mdc1 and mdc2 ) can be added to supply eight
       additional ports.

       The mdc ports are used as follows:

       Port    Usage			  Connector

       0       Console port		  6-pin MMJ on CPU board
       1       Local terminal		  6-pin MMJ on CPU board
       2       Full modem control port	  25-pin D-Sub on CPU board
       3       Local terminal		  6-pin MMJ on CPU board

       An optional asynchronous board provides an additional eight lines:

       4       Local terminal		  6-pin MMJ
       5       Local terminal		  6-pin MMJ
       6       Full modem control port	  25-pin D-Sub
       7       Local terminal		  6-pin MMJ
       8       Local terminal		  6-pin MMJ
       9       Local terminal		  6-pin MMJ
       10      Local terminal		  6-pin MMJ
       11      Local terminal		  6-pin MMJ

       The console baud rate is set to 9600 baud by default.  You can change this by setting the baud environment variable  from  console  prompt.
       Each  communication  port  from	the  serial  line controller behaves as described in the reference page and can be set to run at any of 16
       speeds.	For the encoding, see

       You can establish the state of port 2 (port 6) by specifying either modem or nomodem as part of the file entry.

Restrictions
       The speed default is to 9600 baud on the console port.  The console device must be set for 8-bit character length with one stop bit and	no
       parity. The driver enforces these restrictions; that is, changing speeds with the command may not always work on console ports.

Files
       Console terminal

       Full modem control or local terminal

See Also
       console(4), devio(4), tty(4), ttys(5), MAKEDEV(8)

								       RISC								    mdc(4)
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