IBM 466DX2/SP Unable to read floppies

[_shameless_]

I'm trying to install msdos from floppy, but no matter what I try it just won't boot from the floppy i have written. It will either just hang on a black screen or blinking cursor, or throw an error to replace disk. I've tried swapping the floppy drives and that does not change anything, and I know for a fact the drive I'm using works as it boots the floppy I made just fine on another pc i have.

I'm at a loss here, I've checked in the BIOS and there's no weird settings there, and the jumpers on the main board look to be in good order. I have a trident vesa card, an sb16 isa card, and a 3com ethernet isa card plugged in. I've also tried removing the cd drive and hdd, but that also makes no change. Drive does attempt to read, I can hear it kick on after the POST and sometimes it will get to the booting dos screen but just hang there(when booting off the floppy). Floppy controller may be possible, as the disks I've tried work just fine on other pc's. Is that a certain chip on the mainboard?

I did install dos 6.22 on another pc and then plug the hard drive into my ibm so I have an os now, and when I try copying files on floppy disks to the ? drive it say "Invalid Directory" and when i try formatting the disk I always get bad track 0 error and fails.

 

 

Any ideas? My gut tells me it could be a faulty cap, but I haven't given it a good look over yet

[wierd_w]

cable may be bad.  Try replacing the floppy drive cable.  Also, check to be sure the drive light is not always on. If it is, flip it over.

[_shameless_]

1 hour ago, wierd_w said:

cable may be bad.  Try replacing the floppy drive cable.  Also, check to be sure the drive light is not always on. If it is, flip it over.

That crossed my mind, I did try swapping the cables and no change. I even tried the "bad" cable in another pc and and it read floppies just fine

[wierd_w]

ensure no devices are sitting on the same IO and IRQ resources used by the floppy controller.

 

Floppy controller uses the following resources

 

IRQ6

DMA2

IO 3F0-3F7

 

 

[_shameless_]

On 5/28/2020 at 8:07 PM, wierd_w said:

ensure no devices are sitting on the same IO and IRQ resources used by the floppy controller.

 

Floppy controller uses the following resources

 

IRQ6

DMA2

IO 3F0-3F7

 

 

Think you're on to something, it dawned on me that i replaced the isa graphics card with a vlb graphics card a little while ago and that's about when I started having issues with the drive. I removed all 3 cards(sound card, network card, and vlb card) the drive works perfectly again! Does the vlb card use any differing resources than a standard isa vga card? I never though much of it since i didn't think the vga card would have any conflicts with my floppy drive. Any tips for getting them all to play nice?

[wierd_w]

I would do incremental card installations, until you identify the actual problem child.

 

I personally suspect the NIC or soundcard.  Here is why:

 

Both of those devices need IRQs, and the soundcard needs a DMA.  While it should NOT have been an available option to set with jumpers, it is theoretically possible that one of them is sitting on IRQ6, and or, sitting on DMA2.  VGA, if it grabs and IRQ, tends to live on IRQ9.  Soundcards tend to live on IRQ5 or IRQ7 (And frequently smashed into LPT ports, which use those IRQs), with DMA1 and DMA5.  NIC tends to live on IRQ2, IRQ3, or IRQ10.  (And as such, often smashed serial ports that live on IRQs 2 and 3)

 

Both Soundcard and NIC also need memory IO ranges. Ensure that their base IO ranges are not colliding with 3F0-3F7 range.