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- From: tim@appenzell.cs.wisc.edu (Tim Theisen)
- Newsgroups: comp.sys.ibm.pc.rt
- Subject: Re: serial ports at >4800 baud?
- Message-ID: <tim.712508648@appenzell>
- Date: 30 Jul 92 15:04:08 GMT
- References: <0eR3UD200VsnQrw1om@andrew.cmu.edu>
- Sender: news@daffy.cs.wisc.edu (The News)
- Organization: U of Wisconsin CS Dept
- Lines: 41
-
- Robert Andrew Ryan <rr2b+@andrew.cmu.edu> writes:
- > I am trying to configure some RTs as X terminals to be connected to our
- > network via slip. They are floor models and have two built in serial
- > ports, however I have been unable to get reliable results at over 4800
- > baud, I get garbage and dropped characters.
-
- The device driver in the kernel for the serial ports on the mother board
- does not work reliably at speed over 2400 baud. The device driver needs
- to be rewritten (and I doubt that anyone will do it.)
-
- > Also if I have hardware flow control set on in the modem once I connect
- > to our annex box it just sits there, if I switch the modem back to
- > XON/XOFF and disconnect and re-connect to the modem (before it drops the
- > annex connection) I get a bunch of backed up data from the annex. When
- > connected to an RS/6000 9600 baud and hardware flow control seem to work
- > ok with the same annex.
-
- The device drivers for either type of serial port did not support hardware
- flow control.
-
- > I seem to remember reading a post here maybe a year ago about the chip
- > driving the serial line having only a 1 character buffer, but that it
- > was pin compatible with one with a 16 character buffer. Or was that
- > about the 4 port serial card?
-
- The AT Serial/Parallel card and the 4 port (unbufferd) card uses a NS16450
- uart. This can be replaced with a NS16550AFN. (I just clipped the old
- uart out of an AT Serial/Parallel card and soldered in a socket and inserted
- the NS16550AFN into the socket.) This will provide reliable connections
- up to 9600 baud. To achieve even faster speeds, compile the kernel with
- the a new copy of asy.c that was hacked over by Peter Honeyman and then
- lightly modified by me. The new chip and software together reliably handle
- 38,400 bps and hardware flow control.
-
- Hope this helps, ...Tim
-
- Tim Theisen Systems Programmer
- Internet: tim@cs.wisc.edu Department of Computer Sciences
- UUCP: uwvax!tim University of Wisconsin-Madison
- Phone: (608)262-0438 1210 West Dayton Street
- FAX: (608)262-9777 Madison, WI 53706
-