Were you able to see the full capacity before deleting the partitions? I'm asking because the number is suspiciously the same as the classic BIOS limit.

Yes, the fdisk showed lot more megabytes. It crossed my mind also, but then I used Windows 98 boot diskette and the result was the same.

I just had the same with a 540MB Seagate HDD. It has slightly more than 1.024 cylinders but the BIOS of my 486 board can’t handle that so I ended up with about 520MB.

What does BIOS detect the drive as?

When detecting the drive in BIOS - is there "LBA" option?
If there is - just use it.
If not, then the BIOS is limited to about 500 MB.
You can override BIOS limits with software like Ontrack Disk Manager.

Grzyb thanks a lot. In the System Configuration table after the POST screen there was 853MB whether the option was set in BIOS for NORMAL or LBA for this HDD. But I set the option to LBA, used MS-DOS boot diskette and I fdisked the drive again. Now I have 813MB. I sys the drive but after computer restarts, there is no Loading MS-DOS. There are som Linux Grub leftovers. How can I get rid of 'em?

boot from dos diskette again and type
fdisk /mbr

I was searching the internet like crazy and there are some pretty complicated stuff, but you gave here this genius and simple solution. Thanks a lot 😀. The fdisk /mbr command saved the day.