Re: tlug: Re: ISDN problems

[Chris Sekiya <chris@example.com>]

On Mon, 9 Nov 1998, Howard Abbey wrote:

> It's desired, and also an explanation of why cua* was used in the first
> place, if you know.

Okay.

UNIX didn't used to have bidirectional serial lines.  One device was used
for inbound connections (ttyS*, in Linux ... I misremember the SunOS
device), one was used for outbound connections (cua*, in Linux).  For the
TLUG folks out there who remember getty_ps: this was the reason that the
altline/altlock directives existed -- both lines needed to be watched,
because all hell would break loose if two processes tried to talk to the
same physical device via two different logical devices.

The linux kernel received bidirectional serial lines over a year ago
(IIRC).  Now ttyS* and cua* devices are treated identically.  cua* support
is still there for compatibility reasons, but it'll eventually go away.

-- Chris


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