Path: utzoo!attcan!uunet!lll-winken!ames!netsys!ziggy!scotty
From: scotty@ziggy.UUCP (Scott Drysdale)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Multiple Serial Ports
Message-ID: <159@ziggy.UUCP>
Date: 18 Jan 89 05:11:18 GMT
References: <8812150227.AA09671@postgres.Berkeley.EDU> <14049@oberon.USC.EDU> <554@sunkisd.CS.Concordia.CA> <3241@sugar.uu.net> <147@ziggy.UUCP> <373@madnix.UUCP> <150@ziggy.UUCP> <385@madnix.UUCP> <154@ziggy.UUCP> <347@antares.UUCP>
Reply-To: scotty@ziggy.UUCP (Scott Drysdale)
Organization: Un*x Link,Frederick Md.
Lines: 24

In article <347@antares.UUCP> jms@antares.UUCP (Joe Smith) writes:
>[I've changed the title and sent followups to comp.sys.amiga.tech]
>One killer problem that I have come across is when the terminal at the other
>end demands immediate response to XON/XOFF.  For instance: Lets say you have
>smooth-scrolling VT100 terminal running at 9600 baud.  As the host tries to
[... stuff deleted ...]

yes, that's a good argument for the CPU-on-board approach, and i think
i mentioned it in my original posting.  XON/XOFF processing is one of the
things that my polling routine on the on board CPU will perform every
millisecond for each of the 8 ports, stopping the UART TX cold, with
at most 3 bytes leaking out of the transmitter.  unfortunately, the CPU
i would use (186 at 8Mhz) isn't fast enough to put hardware handshake
polling in there too, so the maximum latency for that would be much
higher (probably around 20 bytes).  if it is a problem, the 8530's built-in
hardware handshake could be enabled, but RS232 being the "standard" that it
is that won't make everyone happy.

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  --Scotty