ISA network card works fine with mechanical HDD but can't find an IRQ when running off SD to IDE adapter \ VOGONS

ISA network card works fine with mechanical HDD but can't find an IRQ when running off SD to IDE adapter

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First post, by Bam Stroker

Posted on 2018-10-17, 12:46

Bam Stroker Offline

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Hi guys, long time lurker first time poster.

I'm having an issue with a network card on my 486 and I'm hoping somebody here might be able to point me in the right direction for a solution. I obtained the PC a few weeks ago and it's been going great, however it was becoming tiresome shuttling floppy disks back and forth as I copied games over from my main PC so I decided to invest in a network card so I could copy files over via FTP. I found a new-in-box ISA SMC EtherEZ 8416T on eBay, installed it and it worked great.

Today I decided to move ahead with my plan of replacing the 170mb mechanical HD in the PC with one of the SD to IDE adapters I saw on Phil's Youtube channel. I even went so far as to find the same one he had used:

I plugged it in and it worked great. I formatted it, reinstalled DOS 6.22 and and Windows 3.11 from floppies and then began copying the essentials over from a backup of the old drive. I even copied the old autoexec.bat and config.sys because I've spent weeks tweaking the system and wanted a 1:1 duplicate of the old HD so I wouldn't have any headaches, but turns out I've got one anyway!

With the original hard drive installed I can run the network card's DOS configuration utility and the tests go sweet and it will work fine in Windows 3.11:

However when running off the new SD to IDE adapter, even though I'm sure everything is set up same as on the other drive I get a message about it being unable to find a free IRQ:

The card appears to be configured the same way on both drives when I fire up the configuration utility. The following screens show all the same settings no matter what drive I'm using:

I've tried several different IRQ settings, disabling/enabling PnP etc. but nothing seems to have an effect.

Finally, here are some dumps from the IRQ page of Microsoft Diagnostics for both the old drive when the network card works and the SD to IDE drive when it's borked:

1IRQ dump from MSD when working:
2
3    IRQ  Address    Description       Detected            Handled By
4    ---  ---------  ----------------  ------------------  ----------------
5      0  0F88:15B6  Timer Click       Yes                 SOFTMPU
6      1  0765:1923  Keyboard          Yes                 Block Device
7      2  F000:E36D  Second 8259A      Yes                 BIOS
8      3  F000:E36D  COM2: COM4:       COM2:               BIOS
9      4  F000:E36D  COM1: COM3:       COM1:               BIOS
10      5  0F88:1575  LPT2:             No                  SOFTMPU
11      6  05CE:00B7  Floppy Disk       Yes                 Default Handlers
12      7  0070:06F4  LPT1:             Yes                 System Area
13      8  0F88:1505  Real-Time Clock   Yes                 SOFTMPU
14      9  F000:E3BC  Redirected IRQ2   Yes                 BIOS
15     10  F000:E36D  (Reserved)                            BIOS
16     11  F000:E36D  (Reserved)                            BIOS
17     12  118B:1DE7  (Reserved)        PS/2 Style Mouse    MOUSE
18     13  F000:E3C5  Math Coprocessor  Yes                 BIOS
19     14  05CE:0117  Fixed Disk        Yes                 Default Handlers
20     15  F000:E36D  (Reserved)                            BIOS

1IRQ dump from MSD when NOT working:
2
3    IRQ  Address    Description       Detected            Handled By
4    ---  ---------  ----------------  ------------------  ----------------
5      0  0F7F:15B6  Timer Click       Yes                 SOFTMPU
6      1  0766:1923  Keyboard          Yes                 Block Device
7      2  F000:E36D  Second 8259A      Yes                 BIOS
8      3  F000:E36D  COM2: COM4:       COM2:               BIOS
9      4  F000:E36D  COM1: COM3:       COM1:               BIOS
10      5  0F7F:1575  LPT2:             No                  SOFTMPU
11      6  05CE:00B7  Floppy Disk       Yes                 Default Handlers
12      7  0070:06F4  LPT1:             Yes                 System Area
13      8  0F7F:1505  Real-Time Clock   Yes                 SOFTMPU
14      9  F000:E3BC  Redirected IRQ2   Yes                 BIOS
15     10  F000:E36D  (Reserved)                            BIOS
16     11  F000:E36D  (Reserved)                            BIOS
17     12  1182:1DE7  (Reserved)        PS/2 Style Mouse    MOUSE
18     13  F000:E3C5  Math Coprocessor  Yes                 BIOS
19     14  05CE:0117  Fixed Disk        Yes                 Default Handlers
20     15  F000:E36D  (Reserved)                            BIOS

I'm hoping it's something simple I've forgot to install or configure but I've been at this for hours and my brain has stopped working. Hopefully it's not a problem with the SD to IDE adapter itself and how it uses system resources because it would be a real drag if I had to choose between it or keeping the network card working.

Thanks!

Reply 1 of 8, by AlaricD

Posted on 2018-10-17, 15:17

AlaricD Offline

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Did you have to use a dynamic drive overlay to use the larger capacity of the SD card? It may have done some memory range remapping. The timer click, keyboard, real-time clock, and LPT2 are all in different I/O ranges. I'm not sure that can be a function of the SD adapter alone, since that should look like an ordinary drive on the IDE port. The IDE port itself didn't get remapped.

Reply 2 of 8, by bjwil1991

Posted on 2018-10-17, 15:27

bjwil1991 Offline

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Looks like the LPT1 port's IRQ is conflicting with the network card. I'd disable the LPT1 port since that's the root cause, or change the IRQ on the network card to a different IRQ address. I had an issue with my network card not working in Windows (cannot detect the card) and it turned out the address space on my network card was using the same as the sound card's MPU-401 address space. Changed it, and it has been working ever since. Also, welcome to Vogons, mate.

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Reply 3 of 8, by AlaricD

Posted on 2018-10-17, 20:03

AlaricD Offline

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bjwil1991 wrote:
Looks like the LPT1 port's IRQ is conflicting with the network card.

Yet LPT1 using IRQ7 doesn't break anything when the mechanical drive is used. The IRQs aren't changing, the addresses are. This is why I suspect a DDO.

Reply 4 of 8, by bjwil1991

Posted on 2018-10-17, 20:21

bjwil1991 Offline

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Good point right there.

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Reply 5 of 8, by AlaricD

Posted on 2018-10-17, 20:38

AlaricD Offline

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Bam Stroker wrote:
I plugged it in and it worked great. I formatted it, reinstalled DOS 6.22 and and Windows 3.11 from floppies...

No mention of it there, though.

But the adapter should be transparent to the HDD controller, with the only change needed that the 2GB (or larger, I can't read the number with certainty) requires different geometry from the original HDD. Unless it did mean changing from CHS to LBA mode and that is what threw things around. Maybe clone the CF card, then switch back from LBA to CHS (with the reduced capacity as expected) just to see if things remap to match when the 170MB drive was used.

Reply 6 of 8, by bjwil1991

Posted on 2018-10-17, 21:35

bjwil1991 Offline

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Also, some 486 motherboards were stuck at the 504MB limitations, whereas later boards (like my old PCChips M912 v1.7 with genuine L2 cache) supported up to 7.8GB and what size is the SD card? My Packard Bell Pack-Mate 28 Plus would throw a fit if there was a hard drive bigger than 3.2GB installed, but, it'll detect my 4.6GB HDD as 700MB in the BIOS, but, with the XT-IDE Universal BIOS, it detects the full storage.

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Reply 7 of 8, by AlaricD

Posted on 2018-10-18, 14:37

AlaricD Offline

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bjwil1991 wrote:
Also, some 486 motherboards were stuck at the 504MB limitations

Right, and enabling LBA in the BIOS for the ones that don't have the 504MB limitation could also result in these addresses moving around-- or it could be the DDO (if one was used) that did that. We'll have to wait for more information from the OP to know what's happening there.

Reply 8 of 8, by Bam Stroker

Posted on 2018-10-19, 04:21

Bam Stroker Offline

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Thanks for your replies so far guys.

I'm not running any DDO program. Although the SD card is 16gb (the smallest I could find) it detects at 528mb which is the largest the BIOS will support.

Additionally my PC is an IBM that has a VERY limited set of features in the BIOS. I've never actually need one with so few options before. Accordingly there are simply no options for enabling or disabling LBA and other drive-related features.

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