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From: grege@gold.gvg.tek.com (Greg Ebert)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: How to set serial port to 115k baud?
Message-ID: <1841@gold.gvg.tek.com>
Date: 7 Jan 91 22:28:53 GMT
References: <1991Jan5.034731.15478@d.cs.okstate.edu> <1839@gold.gvg.tek.com> <3815@ns-mx.uiowa.edu>
Organization: Grass Valley Group, Grass Valley, CA
Lines: 34


 williams@umaxc.weeg.uiowa.edu.UUCP (Kent Williams) writes:
>>
>> S T U F F   D E L E T E D
>> { Regarding the 16450 ACE }
>
>You can't run asynchronous communications with a divide by 1.  The reason
>(which EE types all seem to know, but only tell software people after they
> [...]

If you were more familiar with the 16450, you would know that it has
an *internal* divide-by-16 before the TX/RX shift registers. When you
program a divisor of 1, you get the standard 16x internal clock. Even if
you drive it with an external clock, it's STILL divided by 16. 

The device is also asynchronous, and at the mentioned speed, violates
RS232C spec, which is why I asked --

>>
>>What, pray tell, are you talking to at this speed ? 
>>

>Lots of things.  Usually you go synchronous, though, in which case you
>wouldn't bother with a 16450; you'd use a Zilog SIO.  I've heard of
>115K baud fast-wire transfers, but I think they do that with
>bit-banging and timing loops.

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