Date   : Fri, 22 Dec 2006 09:21:53 -0000
From   : dl.harper@... (David Harper)
Subject: Hard or Soft Sectored Drives

Ian Wolstenholme wrote:


> Could anybody explain the difference between hard
> and soft sectored drives, in simple "DFS-user-guide-
> think-of-a-disc-drive-as-a-filing-cabinet-with-drawers"
> type lay language if possible!

Hard sectored disks had a physical mark at each sector. This meant a whole 
ring of index holes, one for each sector, rather than just a single hole to 
mark the start of the track.

I have not seen one of these disks for a very long time. IIRC the technique 
was used for the old 8-inch floppy disks. (We are talking early 1970's 
technology here, before 5.25-inch disks were thought of.)

> ...

> Looking at Superform, it's set up for soft-sectored
> drives but what is confusing me a bit is that the
> final byte in the 24-byte control block is used to
> set the number of sectors per track, but this
> information is not sent for soft-sectored drives.
> I would have thought this sector-per-track
> information would be needed for Superform to
> format correctly.

One can only guess here. I would suspect that Superform may format a whole 
track at a time (as modern formatting programs do) if soft sectors are used. 
Thus there is a single formatting action per track, possibly with no option 
as to how many sectors are included. On the other hand, if the sectors are 
hard then each sector will have to be formatted separately, waiting for the 
index pulse each time, and so a sector counter will be needed.

David Harper