Let's go over hard disk drive (hdd) organization. This is a good overview of the data:
It shows the 1st level, called "low-level formatting" (LLF) or "physical formatting". That's done by the manufacturer, and you can probably re-do it yourself with a program written by the mfr or a knowledgable person. LLF has changed over the years; generally, you are able to do less with it than with hdds from the 1990s. For instance, older disks could be re-LLF'd to change the number of sectors used; for instance, if you got a drive with 16 sectors, you could try to LLF it as 8, making larger sectors. But things changed, as physical organiztion became more virtualized (famously, lying to the computer's BIOS to get around size limitations). Nowadays, you'd have to be a greater expert with hdds to understand LLF ...
but still there should be place for virii to hide here.
The 2nd level is where the virii trouble starts: "partitioning". All those sectors can be cut up into contiguous chunks called partitions, and which partition you use for which OS is your decision. There are now many types of partitions (here's a list:
Partitions have nothing whatsoever to with each other except through two linkages: the OS currently running, and the Partition Table (PT). The PT was written to the "first" sector as soon as the first partition of any kind was made. According to this link (
the PT contains "executable code" and the "Master Boot Record" (MBR). The MBR is a directory of the partitions on that hdd. So, the trouble is really in that section of executable code. Drive overlays and boot managers try to fit themselves into that tiny space (446 bytes), as well as particularly ambitious virii.
Hence, if you boot from a floppy disk and then wipe out your partitions, I find it hard to believe that a virus is still on the hard disk (in the
virulent sense, since the 1s and 0s still exist across the now-unaccounted sectors on the disk platters). Now perhaps I'm not entirely educated in when the PT is written.
If LLF writes the PT, then a virus is still in those 446 bytes, and adding a new partition
may not overwrite them. If so, then it's true that something must be done about the PT if an infection in it is suspected. But you can use things like Partition Magic to re-write the code in the PT. But you can also do that with simple partition programs, like PART.EXE ... and we don't need to surf the mfr's website for their LLF software.