Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!uw-june!witold
From: witold@cs.washington.edu (Witold Paluszynski)
Newsgroups: comp.unix.i386
Subject: Re: using NS16550A UARTs with a dumb serial card (386/ix)
Message-ID: <10233@june.cs.washington.edu>
Date: 22 Dec 89 01:12:50 GMT
References: <10231@june.cs.washington.edu>
Reply-To: witold@june.cs.washington.edu (Witold Paluszynski)
Distribution: usa
Organization: University of Washington, Computer Science, Seattle
Lines: 27

In article <10231@june.cs.washington.edu> I write:

>I have an Everex EV170B IO card with 3 serial lines on it.
>I just tried using it with the NS16550A UART chips, which
>have FIFO queues for TX and RX and are supposed to be supported
>by 386/ix.  No go.  It doesn't work.  What is strange is that

After I received some responses to my message I realized that I
didn't make myself clear.  The Everex EV170B IO board doesn't
work with the NS16550A UARTs.  The board does not work, period.
Like you lost your serial ports.  I never got to the point of
trying to enable the UART's FIFOs.  I know the description of the
16550A says it powers up in 16450 mode.  But it appears that it
is only FUNCTIONALLY equivalent to a 16450.

But unfortunately the 16550A is not pin-compatible with the
16450.  Two pins (24 and 29) on the 16550A have different
functions than on the 16450 (where 29 is NC and 24 is CSOUT).
Some boards may ignore these pins and work with the 16550A.
The Everex EV170B is not one of them.

This is the result of my investigation of the problem.
If someone has any info indicating how to overcome the
pin incompatiblity problem I would appreciate hearing it.
Otherwise I have three unused NS16550A's for sale.

Witold