The most common way to solve this was with the use of what is known as a DDO: https://en.wikipedia.org/wiki/Dynamic_drive_overlay
Basically it's a small BIOS extension that is installed to the boot sector of your drive.
Various vendors would include a DDO with the drive (they included a floppy with disk utilities, you can probably still download them somewhere, such as Maxtor's MaxBlast). A common one is EZ-Bios.

Ontrack Disk Manager of the old is just the perfect fit for this purpose. It has OEM versions released by almost all HDD manufacturers of that times. I'm sure I've seen versions from Quantum and Maxtor, and they should still be available somewhere. Seagate also had software for the same purpose, but I'm not sure if theirs based on Ontrack or something else.

I would recommend to go with and LBA ISA or PCI card in one of the slots you have left. Or try to find an bios upgrade for your motherboard.
Iam not really font of that DDO overlay software.. If your boot sectors getting corrupt you cant access the last part of your harddrive..

BIOSes were not upgradable back then. They were stored in ROM rather than in flashram.
So the only way to upgrade your BIOS is to replace the chip. Good luck finding those ROM chips. As far as I know, most vendors never sold ROMs separately anyway. BIOSes simply were not upgraded.

I found a bios update for your motherboard. Dont know if its the right one.. But before updating, i recommend to make a backup from your old bios as spare.

http://web.archive.org/web/19970620074833/htt … 433uud-bios.htm

http://web.archive.org/web/19970620073919/htt … .com/driver.htm

I know there was something there..

I try out that url, but doesnt seems to work. But the good thing is here:

http://www.qooqle.nl/?q=UUD0326S.BIN

I also found information about your motherboard:

http://web.archive.org/web/19970620074553/htt … d/uud/84uud.htm

Robin4 wrote:

I found a bios update for your motherboard.

Ah, I stand corrected!
This is apparently a very late 486 board, which does have a flashable BIOS.
In which case it is somewhat bizarre that such a late BIOS would still have a 504MB limit.
The last PC I had with a limit was my Pentium 133, where I believe the limit was 8.3GB. But that BIOS was not flashable yet.

This motherboard, Biostar 8433UUAD, is a very solid motherboard. One of the few that accepts Cyrix overclocking properly. You can read more on the forums just search this board.

For this board there is a BIOS with 8 GB HDD support: The World's Fastest 486

It may be possible to run a software solution. It's been a little while since I ran NT4.

I'm very surprised you're limited to 504MB - I can believe it being 1024 cylinders, which should be somewhat more (a few GB). Are your cylinder/head/sector values in the BIOS manually set to the standard LBA values, and coupled with a modern LBA capable drive?

There is a large disk support driver for NT3.51/4 available on the net. I ran my 486 with 20MB RAM and an 80GB drive as a torrent server for a while, using NT4 and uTorrent. It did work fine, although if the server ended abnormally it needed hours/days to do the rechecking.

The initial boot partition should be located within the first 1024 cylinders. The remainder are handled by the large disk driver.

Robin4 wrote:

I would recommend to go with and LBA ISA or PCI card in one of the slots you have left. Or try to find an bios upgrade for your motherboard.
Iam not really font of that DDO overlay software.. If your boot sectors getting corrupt you cant access the last part of your harddrive..

You can if you make the recommended overlay recovery boot disk. I've been running ddo on my 386 for a number of years now without any dramas.

Thanks for all the reply! 😀

I havn't had time to further troubleshoot this, I simply just added another hard drive on the second IDE-controller and running the software from that. It's a temporary solution and I want to fix it permanantly. I will definitely check that bios update. The plan is to build something fun with this motherboard once I find a contemporary case 😀