From: harvey@indyvax.iupui.edu
Subject: Re: 3COM503 & Clarkson
Organization: Indiana University
Date: 24 Jul 92 20:34:30 -0500

In article <1682DBD60.CCDH001@UTXVM.CC.UTEXAS.EDU>, CCDH001@UTXVM.CC.UTEXAS.EDU writes:
> I am having trouble getting Clarkson's TN3270 to work with a 3COM503
> Ethernet card and hope someone can help.
>
> The pc is a 286 system using Phoenix bios.  There is about 1200k of RAM
> and there is a coprocessor installed.  I believe it is running DOS 3.3
> though I'm not sure.  It's definitely not 5.0.  The system also has
> PC-TOOLS installed.
>
> What happens is that whenever I try to execute TN3270 the system either
> reboots or completely locks up.  And sometimes on reboot it will say that
> there is some problem with the bios and there is no time set and the time
> will be 00:00 though this will correct itself after the next warm boot.
>
> I've checked things out and I've got the interrupt vector (0x66), the io
> address (0x300) and the interrupt number (3) set the same for the packet
> driver and inside the CONFIG.TEL file.

They aren't supposed to be the same.  If you want to use the packet driver,
specify the network hardware options on the command line you use to load
3c503.com.  For example:

3c503 0x66 0x3 0x300 0x1

for thinnet.  This is the same as using all the defaults:

3c503 0x66

To use the external tranceiver (thicknet):

3c503 0x66 0x3 0x300 0x0

See INSTALL.DOC for details.

If you are using the packet driver, don't specify hardware details in
CONFIG.TEL, because the parameters mean something entirely different!
Instead, use:

hardware=packet	# use packet driver not hardware
address=0	# packet driver class defaulted (default=1=Ethernet II)
ioaddr=66	# software interrupt used by packet driver (0=search).

Notice you DON'T specify "interrupt=" AT ALL.

>                                         I've tried setting the packet
> driver for both thicknet and thinnet cables to no avail.  And I've tried
> telling TN3270 that the hardware is 3C503 and packet without good luck.

Unless you happen to hit on the right combination, randomly changing things
probably won't help much.

> I've been able to get Clarkson's TCP/IP to work successfully on my work
> PS-2/60 and several Zenith 386's and never seen this problem.  Is it
> possible that I've stumbled on some sort of address conflict?

It's possible, but without more information it's pretty hard to tell.
You did run the 3Com diagnostics that came with the card, didn't you?
And it did passed both the internal and network tests with the settings
you are using, right?

If you do run the diagnostics and they fail, the most common causes I've
seen here for these cards are, in order from most to least common:

o   IRQ conflict.  You can change this in software.  Machines with
    a COM2 port usually use IRQ 3 for it.  Not many machine have a LPT2
    port, and usually IRQ 5 is reserved for that, so try IRQ 5.
    If all else fails, run something like MSD and find out what
    IRQs your system is actually using!

o   Shared memory base address conflict.  This is configured by a
    jumper on the card.  Some video cards map to the same addresses used
    by default by the 3C503.  If all else fails, you can disable shared
    memory access to the card at a cost of lower throughput.  Your driver
    must support this mode of operation however.  The 3C503 driver in the
    most recent update of the Crynwr packet driver collection DOES support
    this mode of operation (earlier versions didn't).

o   I/O base address conflict.  You can check these with MSD or Norton
    System Info.  To change requires changing a jumper on the 3C503.

o   One of our hardware people told me something about an 8/16 bit jumper
    that had to be changed on some strange clone here, but I could find
    nothing about this in the 3Com Etherlink II adapter manual.

> I would appreciate any suggestions.  Thanks.
>
>                                       <@>
--
James Harvey    IUPUI OIT Technical Support/Networks
harvey@iupui.edu  uucp: iugate!harvey  bitnet: harvey@indyvax