Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!newstop!texsun!texbell!attctc!chasm
From: chasm@attctc.Dallas.TX.US (Charles Marslett)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 16450/16550 UART question
Summary: Just a few new features on the newer ones
Keywords: UART
Message-ID: <8836@attctc.Dallas.TX.US>
Date: 1 Aug 89 02:33:54 GMT
References: <21200@hodge.UUCP>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 33

In article <21200@hodge.UUCP>, jdm@hodge.UUCP (jdm) writes:
> Three questions:
> 
>     1) Could someone explain the difference between the 8250, 16450,
>        and 16550 UARTs?

They are all 8250s with a few new features.  The 16450 adds some additional
flags and a register for the programmer to save some local data (if he needs
it).  The 16550 (I think) adds several bytes of buffering for the recieved data
so interrupt latency is not nearly so critical.

>     2) Is it possible to replace 16450 UARTs in a serial I/O board
>        with 16550 UARTs with no modifications to the circuit?

I am almost certain that this is true.  We have been testing some hardware/
software designs at STB, and I do not believe there are any jumpers or other
bits of configuring hardware around the UART sockets (and the card takes both
16450s and 16550s, even mixed).

>     3) Give a few mail order references to where one might purchase
>        16550 UARTs and the typical price of same.

Sorry, don't know of any -- I just play with the stuff [Andi buys it...].

> Thanks,
> jdm@hodge.cts.com [uunet zardoz vdelta crash]!hodge!jdm
> James D. Murray, Ethnounixologist	TEL: (714) 998-7750 Ext. 129	
> Hodge Computer Research Corporation	FAX: (714) 921-8038
> 1588 North Batavia Street 
> Orange, California 92667  USA

Charles Marslett
STB Systems, Inc.  <-- apply all standard disclaimers