Subject: Re: getting the mouse to work

From: Mark Phillips <[email-masked]>
Date: Wed, 07 Aug 1996 10:21:15 +1000

>When installing gpm, I set my mouse device to /dev/ttys0... Then, I =
>pointed everything else that wanted a mouse device to /dev/mouse.  =

What is the difference between

/dev/ttys1, /dev/cua1 and /dev/mouse (a soft link)

and when should each be used?

Thanks,

Mark Phillips.  ([email-masked])

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From: "Richard G. Roberto" <[email-masked]>
Date: Wed, 7 Aug 1996 11:24:59 -0400 (EDT)

> Mark Phillips.  ([email-masked])

Mark,

This is an old explanation that I'm not sure still holds
true, but ...

A cu device is for DCE devices (Data Communications
Equiptment), basically modems, etc.  A tty device is for DTE
devices (Data Terminal Equiptment), basically terminals,
serial input devices (mice), etc.  The /dev/mouse should be
a link to /dev/ttyxx where xx is probably S0 or S1, etc.
You don't need to have /dev/mouse to have the mouse work,
its just there to conveniently identify the mouse port.

I hope that's helpful, and if anybody knows a better, more
modern explanation, please do :-)

Good luck!

Richard G. Roberto
[email-masked]
201-739-2886 - whippany, nj

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From: Sherwood Botsford <[email-masked]>
Date: Fri, 9 Aug 1996 09:33:31 -0600

> modern explanation, please do :-)

CAVEAT I'm an ignoramlepuss about Linux/Debian.

Under Nextstep, the serial ports work like this:

     /dev/ttya      /dev/ttya (/dev/ttyb) is used for "incoming"
                    connections from directly connected terminals
                    without CTS/RTS flow control.

                    When /dev/ttya is open(2)'ed, the device
                    driver asserts the DTR (data terminal ready)
                    signal.  Opens of the /dev/ttya device name
                    do NOT block waiting for the RS-232 DCD (car-
                    rier detect) signal to be asserted.
                    /dev/ttya should be specified in the file
                    /etc/ttys for directly connected terminals.

                    If a serial line is opened with the /dev/ttya
                    device name, it may not be opened with the
                    /dev/ttyda or /dev/cua device names.

     /dev/ttyfa     /dev/ttyfa (/dev/ttyfb) operates identically
                    to /dev/ttya except that RTS/CTS flow control
                    is supported on 68040-based systems.  See the
                    section below on RTC/CTS flow control.

     /dev/ttyda     /dev/ttyda (/dev/ttydb) is used for "incom-
                    ing" connections from modems.

                    When /dev/ttyda is opened, the device driver
                    asserts DTR and then blocks waiting for the
                    modem to assert DCD (indicating that a con-
                    nection has been established with a remote
                    modem).  When DCD is asserted by the modem
                    the open system call returns.  If DCD is
                    deasserted by the modem, further reads and
                    writes to the device will return the error
                    EIO (i/o error); if the tty is the control-
                    ling terminal for the process a SIGHUP will
                    be sent to the process.

                    /dev/ttyda is typically used in the file
                    /etc/ttys for connecting modems used for
                    dial-up logins.

                    If a serial line is opened with the
                    /dev/ttyda device name, it may not be opened
                    with the /dev/ttya.  A serial line opened
                    with the /dev/ttyda device name may also be
                    opened with the /dev/cua device name.  Inter-
                    locks between the /dev/ttyda and /dev/cua
                    device names are described below.

     /dev/ttydfa    /dev/ttydfa (/dev/ttydfb) operates identi-
                    cally to /dev/ttyda except that RTS/CTS flow
                    control is supported on 68040-based systems.
                    See the section below on RTC/CTS flow con-
                    trol.

     /dev/cua       /dev/cua (/dev/cub) is used for "outgoing"
                    connections to auto-dial modems.

                    When /dev/cua is opened, the device driver
                    asserts DTR and does NOT block waiting for
                    the modem to assert DCD.  No action is taken
                    by the driver when the modem asserts or de-
                    asserts DCD.

                    /dev/cua is typically used by programs like
                    "uucp" and "tip" that need access to auto-
                    dial modems.

                    If a serial line is opened with the /dev/cua
                    device name, it may not be opened with
                    /dev/ttya.  A serial line opened with the
                    /dev/cua device name may also be opened with
                    the /dev/ttyda device name.  Interlocks
                    between the /dev/ttyda and /dev/cua device
                    names are described below.

     /dev/cufa      /dev/cufa (/dev/cufb) operates identically to
                    /dev/cua except that RTS/CTS flow control is
                    supported on 68040-based systems.  See the
                    section below on RTC/CTS flow control.  WARN-
                    ING: To avoid locking problems with tip and
                    uucp, all reference to the "cu" device for a
                    particular serial port must be of the same
                    flow control type.  E.g. tip should not refer
                    to /dev/cua while uucp refers to /dev/cufa.

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From: Rob Browning <[email-masked]>
Date: 09 Aug 1996 13:39:21 -0500

> CAVEAT I'm an ignoramlepuss about Linux/Debian.

[ good info about serial ports deleted ]

I do recall a discussion recently where someone posted text from the
maintainer of the Linux kernel's serial port code that essentially
said that cua* devices were no longer really supported, and that you
should always use ttyS* when possible.

I was having some trouble with cua* at the time (for dialout), and
sure enough, switching to ttyS* fixed the problem.

--
Rob