I can give you some tips on the software part, even though the card worked initially, there might be a conflict with newly installed software on your IBM. Try booting into MS-DOS Safe Mode and see if the card is detected there. This can help identify software conflicts which can give you a path to follow and not wonder blindly with your troubleshooting.
As for the hardware part, since the 3c5x9cfg program isn't detecting the card in the IBM, you might need to manually configure the IRQ and base address in the IBM's BIOS setup.

kevin223 wrote on 2024-07-23, 14:46:

I can give you some tips on the software part, even though the card worked initially, there might be a conflict with newly installed software on your IBM. Try booting into MS-DOS Safe Mode and see if the card is detected there. This can help identify software conflicts which can give you a path to follow and not wonder blindly with your troubleshooting.
As for the hardware part, since the 3c5x9cfg program isn't detecting the card in the IBM, you might need to manually configure the IRQ and base address in the IBM's BIOS setup.

Thanks kevin
sadly I have tried booting in safe mode, (using dos 6.22) with no drivers and it doesn't detect it. Also the ibm bios only lets me to change date, time and disable serial and paralel ports (i did that already)... unless there is a hidden setting that someone know and wants to share.

Run Microsoft Diagnostics MSD in DOS and check available Resources IRQ, DMA, etc…..

Intel486dx33 wrote on 2024-07-23, 16:08:

Run Microsoft Diagnostics MSD in DOS and check available Resources IRQ, DMA, etc…..

If MSD says an IRQ is reserverd by the bios , like IRQ 10 or 11 in my case. It means is it available or not?

An irq reserved by the bios would be unavailable to anything else.

Here is a screenshot a took yesterday.
I know for a fact that IRQ 5 is used by the ESS 1668 soundcard, the only other card in system.
I have disabled LPT and serial port , ancient IBM tech support documents point for COM1 : IRQ 4, 3F8 , COM 2: IRQ 3, 2F8 . LPT: IRQ 7 , ADDRESS: 3BC, 378 , 278 (Parallel 1, 2, 3).
Should I try one of those combinations? , do you see another lead in the screenshot?

I don't think it's even assigning the network card any irqs, from what I can see in the image.

That isn't what reserved means.

The IRQ info in MSD really isn't definitive. Not singling anyone out but it really isn't a useful source of info. It doesn't know anything about PCI or ISA Plug and Play or your Plug and Play BIOS (all of which are methods to ask the system for IRQ assignments that postdate MSD) so that list is not useful or accurate.
It operates by checking the interrupt vector table to identify which driver or TSR is handling a particular interrupt (so if a card is jumpered to a particular interrupt but you haven't loaded a driver, or the driver is bundled into EXEs that use that piece of hardware it is invisible to MSD) along with some hardcoded assumptions. This is why, even if you have a Sound Blaster card installed, it will report IRQ 5 as not detected and suggest it's assigned to LPT2:.

I would suggest reconfiguring it back to a fairly "neutral" configuration like port 0x300 and IRQ 10 as you said. If you can't get it going with DOS then maybe boot into an old Linux distro like Slackware 3.9 and see if the kernel can probe for it.

Is there a better utility for this? I tried System info that comes with Phil's benchmark tools but the info is more or less the same.

Try HWINFO16 (or plain HWINFO since it's a 386)

Yesterday I tried
- Cleaning a ISA slot with isopropylic alcohol, and the 3com card with an eraser and alcohol
- Setting IRQ 3, 4, 7,... and 10 in my k6 computer ,No PNP mode, and ...
- Inserting the card in the slot occupied by the working sound card.
No progress so far.
So as last measure i took of the battery and will try when i get home, my expectations are low at this point, it seems that the ibm wants to hate the 3com card.

The K6 picks it up right away---

MarmotaArmy wrote on 2024-07-24, 14:37:

The K6 picks it up right away---

Is there a way to disable the L1 cache in the 386SLC? I've had some cards refuse to work with Cyrix CPUs. I say cards but the problem was mostly software, not hardware. I assume you've been trying to run the config program in pure DOS, not the DOS window from Win3?

I could give you my own tool for dumping (and restoring) EEPROM contents on the 509 series. These cards have a specific "unlock" sequence, and 3Com own PnP mode which allows one to reconfigure the settings. All of this is done via I/O and IRQ doesn't matter at this point. That might help you track what resource conflict is preventing the card from working.

Deunan wrote on 2024-07-24, 15:02:

MarmotaArmy wrote on 2024-07-24, 14:37:

The K6 picks it up right away---

Is there a way to disable the L1 cache in the 386SLC? I've had some cards refuse to work with Cyrix CPUs. I say cards but the problem was mostly software, not hardware. I assume you've been trying to run the config program in pure DOS, not the DOS window from Win3?

I could give you my own tool for dumping (and restoring) EEPROM contents on the 509 series. These cards have a specific "unlock" sequence, and 3Com own PnP mode which allows one to reconfigure the settings. All of this is done via I/O and IRQ doesn't matter at this point. That might help you track what resource conflict is preventing the card from working.

Yes please , any help is appreciated. I'm sending you a PM

Check your motherboard manual and jumper settings.
I think there is a jumper to switch between Motherboard video and add on card.

I have the 3c509b Etherlink III in my IBM Ps/2 and it works fine.
I am running the original install of DOS 5.0 and Win3.11
Win3.11 automatically detects the 3c509b upon installing network support.

Put the 3com in the IBM and reset and. Save the updated bios setting.

Intel486dx33 wrote on 2024-07-24, 15:40:

Check your motherboard manual and jumper settings. I think there is a jumper to switch between Motherboard video and add on card […]
Show full quote

Check your motherboard manual and jumper settings.
I think there is a jumper to switch between Motherboard video and add on card.

I have the 3c509b Etherlink III in my IBM Ps/2 and it works fine.
I am running the original install of DOS 5.0 and Win3.11
Win3.11 automatically detects the 3c509b upon installing network support.

Put the 3com in the IBM and reset and. Save the updated bios setting.

The only jumper it has is for disabling password 🙁 . As is mentioned in OP the card was working on the IBM before the case restoration and now it doesn't want to cooperate with the ibm but it has no problems in the K6.

Anyone has experience using the Intel Isa configuration utility , could it help here?

Trouble shooting hardware is a process of elimination.
Find out what’s working and what’s not.

Make sure that ISA slot is working by trying a different card in that slot.
Put the 3com in the K6 and run the 3com configuration utility and set it to default setting except choose to use the TP connection.

I have the 3com 3c509b working in my
IBM Ps/1 486 ( DOS / Win311
IBM P90 Pentium 90 desktop ( Win95 )
IBM Aptiva tower ( Pentium 200mmx ) Win95
IBM Select-a-system desktop ( Win3x

It my favorite retro network card because it’s easy to setup and reliable.
I use it in all my computer running DOS/Win3x/Win95

Intel486dx33 wrote on 2024-07-25, 15:00:

Trouble shooting hardware is a process of elimination. Find out what’s working and what’s not. […]
Show full quote

Trouble shooting hardware is a process of elimination.
Find out what’s working and what’s not.

Make sure that ISA slot is working by trying a different card in that slot.
Put the 3com in the K6 and run the 3com configuration utility and set it to default setting except choose to use the TP connection.
It my favorite retro network card because it’s easy to setup and reliable.

I tried inserting it in the sound card slot (working) which i removed so only the 3com is in. No luck.
I'll try the default config. and maybe IRQ 5 which according to IBM manual is free by default.
I was very happy with it, I was getting 300KB/s connected to my local ftp server.

Isn't the bios configuration done via a dos program on IBM machines? Or were 486-era IBMs not like that?

SOLVED!
Solution at the OP