Think that's a failed lilo.. Linux loader.

Yes. LILO failed, linux was on it. Best way is boot a disk gparted and erase everything. Or DBAN for first few minutes then exit.

Cheers,

A DOS 7/Win 98 boot disk and running FDISK /MBR should clear LILO.

You might be able to do that from a DOS 6 boot disk too, but I can't recall if the command functions the same. Can't hurt to try if that's what you already have to hand though.

Thanks guys

I removed all partitions with fdisk under DOS6.2 and made the 504MB partition.
And I just did the same thing again on a 'modern' PC with this disk and it crashed when I tried to boot after the installation at 'verifying DMI pool data'
I just downloaded DBAN but realized it's 16MB ISO and my 486 does not have a CD yet 😀 And it seems that GParted is a CD ISO also.
I don't have win98 unfortunately. Would the disk manager in win10 remove lilo?

You don't need to have Win 98, just grab a boot disk image from here for example: https://www.allbootdisks.com/download/98.html

Then use another PC with a floppy drive to write the disk image.

You only need to type FDISK /MBR and press enter and you should hopefully be sorted.

Solved!
That switch fixed my MBR 😀

Thanks guys

Yay!

When I had a hard drive that was not able to remove that odd boot sector, it was the windows and fdisk not doing correctly.

Cheers,