slow connection between terminal(8088) and linux box via serial

slow connection between terminal(8088) and linux box via serial

Post by Kenny Helm » Wed, 07 Jan 1998 04:00:00



I connected a 8088 running kermit to a linux box via serial port. I'm
using getty-ps. the connection is working but is slow(10 to 12 char
burst about every 20 secs.) kermit is set with 9600 8n1 vt100 and the
getty is set for 9600.

does anyone know why this is happening?

 
 
 

slow connection between terminal(8088) and linux box via serial

Post by Kenny Helm » Wed, 07 Jan 1998 04:00:00



> I connected a 8088 running kermit to a linux box via serial port. I'm
> using getty-ps. the connection is working but is slow(10 to 12 char
> burst about every 20 secs.) kermit is set with 9600 8n1 vt100 and the
> getty is set for 9600.

> does anyone know why this is happening?

  It is exactly 16 char bursts.

 
 
 

slow connection between terminal(8088) and linux box via serial

Post by Mark Gr » Thu, 08 Jan 1998 04:00:00




Quote:> I connected a 8088 running kermit to a linux box via serial
> port. I'm using getty-ps. the connection is working but is slow(10
> to 12 char burst about every 20 secs.) kermit is set with 9600 8n1
> vt100 and the getty is set for 9600.
> does anyone know why this is happening?

9600 is too fast for the 8088 to keep up with and you are getting
overrun errors which cause kermit to retransmit.  2400 is about the
best you can reliably expect from a 8088 in my experience, unless you
bypass the bios entirely and write it all in assembly.
 
 
 

slow connection between terminal(8088) and linux box via serial

Post by Pat Thoyt » Thu, 08 Jan 1998 04:00:00




> > I connected a 8088 running kermit to a linux box via serial port. I'm
> > using getty-ps. the connection is working but is slow(10 to 12 char
> > burst about every 20 secs.) kermit is set with 9600 8n1 vt100 and the
> > getty is set for 9600.

> > does anyone know why this is happening?

>   It is exactly 16 char bursts.

As a guess - that looks a bit like the linux box has a 16550 serial
chip. These have a 16 character buffer and generally speed up serial
access by using 1 interrupt for the buffer instead of 1 interrupt per
character (as happens on the older chips).

I suggest you look at setserial on the linux box. You can turn off
this feature. There is a serial-HOWTO which might mention this as
well. Also - check your /etc/rc.d/* files. I've used 8088 and 286's
in this way and never had this problem (otherwise I'd give you an
explicit answer). I suspect you have a default setserial command
designed for a fast modem being run at bootup.

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slow connection between terminal(8088) and linux box via serial

Post by Stuart R. Full » Thu, 08 Jan 1998 04:00:00




:
: > I connected a 8088 running kermit to a linux box via serial
: > port. I'm using getty-ps. the connection is working but is slow(10
: > to 12 char burst about every 20 secs.) kermit is set with 9600 8n1
: > vt100 and the getty is set for 9600.
:
: > does anyone know why this is happening?
: >
:
: 9600 is too fast for the 8088 to keep up with and you are getting
: overrun errors which cause kermit to retransmit.  2400 is about the
: best you can reliably expect from a 8088 in my experience, unless you
: bypass the bios entirely and write it all in assembly.

More likely that the IRQ for the serial port does not agree with what the
kernel thinks it is.

Look at the output of:

        $ setserial -bg /dev/ttyS[0-3]

and compare them to jumpers and/of BIOS settings.  If they're wrong, then you
can either change the jumpers or the BIOS settings, or you can use setserial
to change what the kernel think they are.

        Stu

 
 
 

slow connection between terminal(8088) and linux box via serial

Post by Brian McCaule » Fri, 09 Jan 1998 04:00:00



> I connected a 8088 running kermit to a linux box via serial port. I'm
> using getty-ps. the connection is working but is slow(10 to 12 char
> burst about every 20 secs.) kermit is set with 9600 8n1 vt100 and the
> getty is set for 9600.

> does anyone know why this is happening?

Sounds like an IRQ confict.  Check what IRQ the serial port is on.
Check that no other devices are on the same IRQ.

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slow connection between terminal(8088) and linux box via serial

Post by James M Bes » Fri, 09 Jan 1998 04:00:00





> > I connected a 8088 running kermit to a linux box via serial
> > port. I'm using getty-ps. the connection is working but is slow(10
> > to 12 char burst about every 20 secs.) kermit is set with 9600 8n1
> > vt100 and the getty is set for 9600.

> > does anyone know why this is happening?

> 9600 is too fast for the 8088 to keep up with and you are getting
> overrun errors which cause kermit to retransmit.  2400 is about the
> best you can reliably expect from a 8088 in my experience, unless you
> bypass the bios entirely and write it all in assembly.

I have run 8088 systems at 115kb with kermit and others... (this speed
is handy for downloads).  I would guess that the IRQ is incorrect.  Try
hooking a modem up to the serial port on the terminal and see if you can
comunicate with it.  It should echo everything you type as you type it.
 
 
 

slow connection between terminal(8088) and linux box via serial

Post by Kenneth Sanisl » Mon, 12 Jan 1998 04:00:00



>I connected a 8088 running kermit to a linux box via serial port. I'm
>using getty-ps. the connection is working but is slow(10 to 12 char
>burst about every 20 secs.) kermit is set with 9600 8n1 vt100 and the
>getty is set for 9600.

>does anyone know why this is happening?

Yea.. Sounds like you have an IRQ (or perhaps DMA) conflict on one of the 2
systems (I just had that problem with a 33.6 modem <makes i-Net Xtra fun>)
What are the comm ports you have the 2 systems on com# and tty## (or cua#)
(and do you have a sound card in one of them?) because a sound card is
usualy on IRQ-5 (cua2) and the printer is on IRQ-7 (cua3) so only cua1 and
cua2 are free.
 
 
 

1. Connecting and 8088 to my Linux box via serial ports

Right now I have a 386/33DX running Linux.   I also have a 8088 running Dos
(and CP/M when I'm really bored. :)   While eventually I want to upgrade the
8088 to a 386, and get a 486 or higher, I'm still asking now because:
        a) it will be a while (monetary reasons)
        b) I'll still want to do this after I've upgraded.

Neither of the machines have Ethernet cards in them, and I plan on
buying/making a serial cable to link them together (like a laplink cable).  If
this can be done via the parallel port, even better, but I'll use serial for
now.

What I would like to do is connect the serial ports of the two machines, and
using the public domain packet drivers, and Clarkson University's CU/TCP
package, be able to telnet, ftp, etc... from my 8088 PC into my Linux box.

I know that this will probably involve using SLIP in one way or another.  This
is where I need help.  For starters, I don't have a clue on how to set up
SLIP.  I remember trying to do this before, and all the docs kept talking
about DIP, contradicting themselves, and basically being as unhelpful as Unix
docs tend to be.   One of the problems I remember I kept running into, was
phone numbers.  Obviously in this setup, I don't need to dial anything, but
that's all the docs wanted to talk about.  (Besides, the modem is for UUCP :)

Any help from anyone that's done this would be wonderful.  I've looked at the
list of Howto's, but none of them deal with this (unless it's hidden away in
the Ethernet one.)

        Thanks!!!
                -Dan

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