how to use DS-HD floppy disks in Commodore Floppy drives
Who wouldn’t have wondered if they can put 5 ¼" DS-HD disks into Commdore 64, SX-64, VIC-20, 16, 116, Plus 4 floppy drives?
One time there was an urban legend, that HD disks ruin DS drives… we don’t know where this myth came from. This is also one of the Internet nonsenses…
Floppy disks contain a magnetizable layer (DD disks contain iron oxide, while HD disks contain cobalt), on which data can be written by magnetization.
The only difference between DD and HD disks is that the magnetizable layer is applied to the HD disks in such a way that double more data can be written onto it. Therefore, HD disks can also be used backward, in DD format (after formatting). Of course, reversely - HD data on a DD disk – cannot be physically written to.
Everyone has tried to format HD disks on a Commodore computer and it almost always stopped with an error. But why, when DD disks are in a 40 track format and HD disks are in 80 track format? This is true, but only for PC format, this is what everyone forgets.
In the case of a PC, the disk is divided into 40 and 80 tracks, so that HD disks can be formatted and used in DD format.
We, on the other hand, have to use the Commodore standard. What does this mean?
The Commodore 5 ¼” DS-DD disks have 35 tracks and 17-21 sectors per track, while PC 5 ¼” DS-HD disks have 80 tracks and 15 sectors per track. In this case, the trick is in the tracks.
As long as Commodore operates with 35 tracks, PC operates with 80 tracks. Thus, if we try to format an 80-track HD disk to a 35-track DD disk, a so-called crosstalk occurs between the tracks. This means, the formatting process will run, but it will stop with an error sector by sector (we get incomprehensible extra data back while reading).
What can we do to be able to use an HD disk?
The answer is very simple, swipe the disk with a strong magnet. Such a magnet can be for example a speaker magnet. Swipe the magnet on both sides of the disk. The direction of the movement doesn’t matter, the point is to pull the magnet well through all parts.
If our magnet is not too strong or we haven’t pulled it through both sides of the disk well, the formatting will fail again. This is not a problem, we have to re-magnetize our disk and then the formatting will run fine.
Nowadays it is quite difficult to get 5 ¼” DS-DD disks, but DS-HD disks can almost anyone find at home or on a forum. New, unopened DS-HD disks are not rare, however, in many cases, these are cheaper than used DD disks.
More importantly, HD disk manufacturing technology is more modern – DD manufacturing flaws have been eliminated – so HD disks last longer.
You can read the Facebook post about Commodore 5 ¼” DD-HD disks here: