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From: rcpt@urc.tue.nl (Piet Tutelaers)
Newsgroups: comp.unix.bsd.netbsd.misc
Subject: Stop the silo overflows!
Date: 30 Aug 96 18:20:21 GMT
Organization: Eindhoven University of Technology, The Netherlands
Lines: 45
Message-ID: <rcpt.841429221@asterix.urc.tue.nl>
NNTP-Posting-Host: asterix.urc.tue.nl
X-Newsreader: NN version 6.5.0 #10 (NOV)
When you are using internet over a telephone line via SLIP or PPP
and get lot's of silo overflows you probably have an unbuffered
UART on your serial port, like the 8250 or the 16450. With the
introduction of the IBM PS/2 systems the first 16550 UART's were
shipped to provide a 16 byte buffer. But unfortunately the buffering
of the original 16550 did not work. The problem was solved with
the improved 16550A UART. If you run MSD (under MSDOS!), an
application that comes with MS-Windows, you can determine the UART
type of your serial ports (by choosing COMS). The UART type is also
showed when your UNIX boots up.
To solve the `silo overflow' problem you can by a Multi/IO card
with a `real' 16550A, or a card with an extra serial port, like
for example the HAYES ESP card. The Hayes card has a DOSSETUP
utility to configure its port address and IRQ. The port address
can be choosen between 180H and 380H, the IRQ address 3, 4, 5 or
9. Normally COM1 (tty00) and COM2 (tty01) claim IRQ 3 and 4. So
you can choose for example 9 for the Hayes ESP card. Then you have
to add the appropriate lines in your kernel configuration, for
example:
---------- kernel configuration -------------------------
options COM_HAYESP
device com0 at isa? port "IO_COM1" irq 4
device com1 at isa? port "IO_COM2" irq 3
# com2: Hayes ESP serial port
device com2 at isa? port "IO_COM3" irq 9
---------------------------------------------------------
I don't know if the option COM_HAYESP is really necessary. I got the
advice to use it from christos@deshaw.com (Christos Zoulas). CTS
provides interesting technical information about serial ports:
http://comminfo.com/pages/ctsfaq01.htm#q6.
Happy {SLI,PP}P-ing,
--Piet
internet: rcpt@urc.tue.nl __o Piet Tutelaers
bitnet: rcpt@heitue5.BITNET _`\<,_ Computer Center Room RC 1.90
phone: +31 (0)40 474541 (_)/ (_) Eindhoven University of Technology
fax: +31 (0)40 434438 Save nature P.O. Box 513, 5600 MB Eindhoven, NL