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From: gandrews@netcom.COM (Greg Andrews)
Newsgroups: comp.dcom.modems
Subject: Re: WD16C550 UART (was Re: Suitable serial card for H/S modem)
Summary: It's one of the bad ones.
Keywords: 16550 16C550 UART
Message-ID: <24439@netcom.COM>
Date: 17 Feb 91 22:14:27 GMT
References: <6804.27BA1B22@zswamp.fidonet.org> <1991Feb17.005550.4894@cc.helsinki.fi>
Followup-To: comp.dcom.modems
Organization: Netcom - Online Communication Services  UNIX System {408 241-9760 guest}
Lines: 22

In article <1991Feb17.005550.4894@cc.helsinki.fi> 
tmottonen@cc.helsinki.fi writes:
>
>    I have an Orchid memoryboard with serial port, and it says  "(c) WDC'89"
>    and "WD16C550JM" on the chip next to the port. Is this a Western Digital
>    16550 ? And what's the wierd catch ?
>

Yes, that's the Western Digital CMOS version of the 16550 (the "C" in the
part number denotes that it's made of CMOS transistors).  I've seen reports
that this is one of the chips with a bug in it.  I don't recall the details
but I seem to remember that the WD 16C550 has a bug when it's being used in
the FIFO buffer mode at *slow* speeds (below 9600).  If it's used in the
'normal' non-buffered mode, or in buffered mode at high speeds, it seems
to work okay.

Perhaps someone can jump in and confirm or correct me on this...

-- 
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| Greg Andrews      |   gandrews@netcom.COM |
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