cinix wrote on 2022-03-27, 22:48:

Most of the time when the system locks up a red light on the front of the PC turns on, does that help me or is that a generic error?

I expect this is the disk activity light and when it's constantly on usually means there is an issue with either the disk drive of disk controller.

I would look at the drive S.M.A.R.T. to check if there are any reported errors.

cinix wrote on 2022-03-27, 22:48:

I have a 486 PC I recently bought and I've been trying to back up the hard drive. I don't own any other PC's with IDE ports, or […]
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I have a 486 PC I recently bought and I've been trying to back up the hard drive. I don't own any other PC's with IDE ports, or have any other IDE hard drives I could plug into it, which made it difficult. My first attempt was to hook up my laptop and use interlnk/intersvr to transfer the files with xcopy. It was painfully slow, but would have been fine if the PC did not keep freezing.

I eventually found xxcopy16 which let me resume quickly from where I left off after each time it froze. I could copy a couple files, it would freeze, I would reboot and start again. Sometimes it froze right away, other times it might run 10 minutes. It took many days but eventually I made a copy of the drive.

Now I'm trying to understand why it's freezing, and I'm at a loss to how to start debugging the problem. I tried experimenting by enabling/disabling different CPU caches, and I tried running some slowdown programs, none of which helped.

I purchased an IDE-to-SD card adapter thinking that the freezing may just be caused by the interlnk software, but that didn't turn out to be the case. When copying files from the original hard drive to the new "SD card" hard drive I experience the same freezing. I tried running scandisk on both the original hard drive, and the SD card, and they each lock up during the surface scan.

Most of the time when the system locks up a red light on the front of the PC turns on, does that help me or is that a generic error? The motherboard is a UC4914-G (rev 1.0) with a CPU i486 DX2, and 16 MB of RAM.

I'm hoping what I'm describing is common enough that someone may know what is happening, or could give me some pointers.

Before going crazy on what could be the issue with that hard drive / motherboard (yes, it could be a setting in your bios, an incompatibility between the actual hard drive / bios implementation, 32 bit transfers or an actual hardware issue with your motherboard / controller card / hard disk) I'd strongly advise you to buy / rent or borrow a USB to Hard Disk adapter so you can firstly back up that hard drive.

After you're done with that, it could be one of several issues. It could be that the hard drive is a bit too large for the motherboard you're using even if your partition is Fat16/32 it cannot see the end of the drive but the partition DOES point to something that the motherboard cannot see. It could also be that your hard disk has a failing sector in the filesystem descriptor and when anything points to it, it fails to read it. It could be that the controller simply does not like the hard disk you have.

After you've sucessfully backed up your hard disk you might be able to MHDD it. (MHDD is a tool that allows for very low level testing without the need of a dedicated card for it) you can even run it destructively were every sector in the drive will be written and read, and those that are bad will be marked and discarded. (Warning here: this may kill the hard disk, just FYI)

Let us know how everything turns out!

I will second the USB to HDD adapter. Most of them do IDE and SATA.

You can also get internal IDE to SATA adapters but those are going to be less useful for most situations.

I do have (I think) a good backup of the drive. xxcopy16 was only checking file size and timestamp, so its possible that incrementally copying files with the computer locking up left some corrupt . It would be a good idea to run the tool again and checksum the copy. This really needs to be done outside of this computer though.

I have a USB to IDE adapter, but the drive didn't work with it. It's the original hard disk, Conner CFS420A 420MB HDD. I don't think it has S.M.A.R.T., but I could be wrong. I'm a little worried to plug the drive into the cheap USB adapter again as I doubt the adapter was intended for drives this old. It may be better to just buy a newer old PC that has onboard IDE support. I imagine if my only requirement is it has IDE I should be able to find something cheap.

Because I have the same lockup issue with the SD Card to IDE adapter I suspect its not only the Conner CFS420A drive I have a problem with. The disk controller is a good theory. If I purchase a new controller to try and swap out with the current one, is there anything I should avoid?

I think my plan for debugging is:
1. Try new IDE cables
2. Try unplugging anything I don't need (I think this is just the floppy drive and modem)
3. Re-seat the disk controller card and memory.
4. Inspect for any obvious signs of damage (I've done a cursory look over, but it's hard to really tell without taking everything out of the case)
5. Replace the disk controller.
6. Replace the memory.

The problem with replacing parts is I don't have anything that works, so I won't know if my new parts are broken too. I can't think of a better way to go though.

Thanks everyone. Replacing the I/O Card with a different I/O board fixed the problem of the PC freezing.

Glad you got it fixed...

For anyone digging this up in future, another thing to check in this situation is if you've got a large voltage between the case/connector shell grounds between the two machines. Plugging them both into same circuit should help, if not google "ground loops" for info and suggestions.