Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!samsung!rex!doerschu
From: doerschu@rex.cs.tulane.edu (Dave Doerschuk)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: PS/2 serial Port differences
Message-ID: <3824@rex.cs.tulane.edu>
Date: 11 Jul 90 03:30:39 GMT
References: <1990Jul7.114947.4260@cc.ic.ac.uk> <1834@krafla.rhi.hi.is> <1151@gold.GVG.TEK.COM>
Organization: Computer Science Dept., Tulane Univ., New Orleans, LA
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In article <1151@gold.GVG.TEK.COM> grege@gold.GVG.TEK.COM (Greg Ebert) writes:
>The PS/2 uses a 16550, whereas the AT uses a 16450. The 16550 has internal
>transmit and receive FIFOs, which SHOULD be transparent to software, but
>judging by the piss-poor code out there (mislabled as software), I would not
>be surprised people are finding problems. Get the data sheet for the 16550.

I couldn't agree more, there is a lot of staggeringly bad comm software
out there!

Chuck Forsberg (Owen Technology) in his DSZ zmodem implementation mentions
that the only 16650 chips he recommends are:
1)  NS16650AN
2)  NS16650AFN
Both these chips have a 16-deep receive FIFO; but the FIFO must be explicitly
enabled by the communications software.  That is, the default is to not use
the FIFO buffer (this should be true for any 16650).

Chuck specifically mentions Western Digital's WD16650 chip as having problems
operating at speeds less than or equal to 2400 bps.

You might want to crack open your box and look at the chip you've got.  If
its anything other than one of the two listed above, you may want to change
it out.

Dave
doerschu@rex.cs.tulane.edu