Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!ucbvax!bloom-beacon!eru!hagbard!sunic!chalmers.se!mathrt0.math.chalmers.se!d9mikael
From: d9mikael@dtek.chalmers.se (Mikael Wahlgren)
Newsgroups: comp.os.os2.misc
Subject: Re: Serial port and 16550 chip
Message-ID: <1991May29.142252.22685@mathrt0.math.chalmers.se>
Date: 29 May 91 14:22:52 GMT
References: <ignacij.675448326@orion>
Sender: news@mathrt0.math.chalmers.se (Evald Nyhetsson)
Organization: Chalmers University of Technology, Gothenburg, Sweden
Lines: 25

In article <ignacij.675448326@orion> ignacij@orion (Ignacy Misztal) writes:
>I run Kermit under OS/2 using a 9600 baud modem with v.42bis data compression
>that can be connected up to 38,400 baud. A version of Kermit (VIO) runs

>recommend exchanging the common, non-buffered SIO cotroller 16450 by a newer
>chip 16550, with 10 character FIFO. Will OS/2 take advantage of this chip
>automatically, reducing the number of interrupts, or does the application have
>to do it?

Actually the 16550 UART has two 16 bytes FIFOs.  Yes, OS/2 (version 1.2 and
1.3) automaticly take SOME advantage of the FIFO, but to make full use of
them, the program must be programmed with the FIFO's in mind.  The FIFO
support is very easy to use, so I think most modern communication packages
support the FIFO.

The FIFO helps A LOT!  The first thing to do when you use high speed
asynchronous communication is to replace all 8250/16450 with a 16550
and get a program using the FIFO.

It is VERY easy to patch both COM01.SYS and COM02.SYS (OS/2 version 1.3)
to support any speed up to maximum 115 kBaud.  Please write a mail if
interested.  Because of the CPUI-load, I wouldn't recommend this patch
to anyone without the 16550 FIFO though.

Mikael Wahlgren      d9mikael@dtek.chalmers.se