Older systems have bugs/limitations in the bios preventing them to see larger disks which is what you are describing. My pentium 1 will not accept even a 2gb disk.

You can do tricks with software but I have not looked into it myself. Results may vary I suppose.

https://youtu.be/JQh7Yu5_zDM?si=hLQm_LoC3xNX1S-x

Joakim wrote on 2024-04-02, 20:40:

Older systems have bugs/limitations in the bios preventing them to see larger disks which is what you are describing. My pentium 1 will not accept even a 2gb disk.

You can do tricks with software but I have not looked into it myself. Results may vary I suppose.

https://youtu.be/JQh7Yu5_zDM?si=hLQm_LoC3xNX1S-x

I really appreciate the reply, thank you. I did wonder if it was something like that, I was hoping that the small partition would be enough to make it work; looks like a deeper limitation than I thought.

I'll check out the video now, thanks again.

For a 486 system you may need a BIOS extension or dynamic drive overlay (DDO) software to use a drive that size.

Shponglefan wrote on 2024-04-02, 20:51:

For a 486 system you may need a BIOS extension or dynamic drive overlay (DDO) software to use a drive that size.

Thanks. BIOS extension seems to be out of the question from what I can see, but the DDO is a real possibility; I'll let you know if I can get it working.

i have this one below (amazon link) and it works ok with my 486 & 64GB SSD drive.

https://www.amazon.co.uk/gp/product/B07TPBC34F

FYI, this is my MB.. https://theretroweb.com/motherboards/s/rectron-rt-4s3

This may be that missing signal, I forget what it’s called, I think user Rayer? May have made a circuit for this.

Basically newer drives dropped a signal that those older boards looked for, but it can be emulated to make the drive work.

I’ll tag them.

Edit: IOCS16#

They’ve been tagged.

Or it could be that your storage device only speaks LBA and your motherboard only speaks CHS.

It would be interesting if you could put an XTide ( or some other LBA aware) option rom in your system and see if it detects then.

It's not just the size of the partition, but the size of the drive itself. Try limiting it to 128GB using SeaTools as per Phil's guide here and see if that helps.

ubiq wrote on 2024-04-03, 02:47:

It's not just the size of the partition, but the size of the drive itself. Try limiting it to 128GB using SeaTools as per Phil's guide here and see if that helps.

This was the solution, thank you. Instead of using SeaTools, I ended up adjusting the LBA characteristics with Victoria for Windows which has a handy Windows GUI.

Thanks to all who posted!

Sweet! Good job!

Dan386DX wrote on 2024-04-18, 00:20:

ubiq wrote on 2024-04-03, 02:47:

It's not just the size of the partition, but the size of the drive itself. Try limiting it to 128GB using SeaTools as per Phil's guide here and see if that helps.

This was the solution, thank you. Instead of using SeaTools, I ended up adjusting the LBA characteristics with Victoria for Windows which has a handy Windows GUI.

Thanks to all who posted!

Awesome, glad to hear it!

I also tried the seatool solution. It won’t work for me.

My sata attached HDD will only be recognized as strange 126mb device in fdisk. No partitioning etc possibly / can be done but after reboot not applied.
My ata tool furthermore recognizes the disk also as 126mb device sata/pata but furthermore a mysterious scsi device - which seems capacity wise the right device. But this device isn’t accessible from any tool (dfsee, partition magic, ….). Exactly the same result with ssd and also another pata sata adapter.

I’m getting closer to become out of any more ideas.

Any further hints?

Update: after reading through all threads it seems as it this combo 386bios plus sata is simply a nogo. Damn

Marco wrote on 2025-10-15, 18:33:

I also tried the seatool solution. It won’t work for me. […]
Show full quote

I also tried the seatool solution. It won’t work for me.

My sata attached HDD will only be recognized as strange 126mb device in fdisk. No partitioning etc possibly / can be done but after reboot not applied.
My ata tool furthermore recognizes the disk also as 126mb device sata/pata but furthermore a mysterious scsi device - which seems capacity wise the right device. But this device isn’t accessible from any tool (dfsee, partition magic, ….). Exactly the same result with ssd and also another pata sata adapter.

I’m getting closer to become out of any more ideas.

Any further hints?

Update: after reading through all threads it seems as it this combo 386bios plus sata is simply a nogo. Damn

Maybe it’s what I mentioned above

There’s a thread about it somewhere where they were making little modifications to the backside of IDE pinout to add the missing signal

Re: SATA HARD Disk in 286/386 Mobo: Is it possible?

Is this the thread you're looking for?
However, the Gerber data isn't publicly available, so it looks like the only way to do it is to make it yourself.

Thank you for our feedback. I will try to replicate that Pinout solution. But maybe later.

kagura1050 wrote on 2025-10-16, 05:50:

Re: SATA HARD Disk in 286/386 Mobo: Is it possible?

Is this the thread you're looking for?
However, the Gerber data isn't publicly available, so it looks like the only way to do it is to make it yourself.

Yes, I think that’s the one