Date   : Sat, 09 Feb 1991 20:57:00 GMT
From   : agate!bionet!uwm.edu!rpi!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!ira.uka.de!smurf!subnet.sub.net!mcshh!tilmann@ucbvax.Berkeley.EDU (Tilmann Reh)
Subject: 3.5inch HD disk formats: Why not 11*1024

> remember Dave Goodenough claiming that he runs his with 10*1024+1*512
> byte sectors per track, which Tilmann Reh found disgustingly
> incompatible, therefore Tilmann uses 10*1024 and frowns on Dave.
> Anyhow, we were just re-writing the formatting routines of my disk
> controller. We came across something very strange. We claim that
> 11*1024 is legal ! Here's how the numbers work out:

I never told something about (nor ever used) a 10x1024 byte 3.5" HD format.
The only 3.5" HD format I ever defined was 11x1024 byte, giving 1760k
per disk. Perhaps at least Christoph remembers that I was the one who gave
him the algorithms and data sheets for gap calculation (resulting in the
format mentioned above).
Sometime ago someone else spreaded a word about things I would have said
concerning format definitions (kind of the above), which are also absolutely
nonsense. Seems like someone is misusing my name?

However, the discussion with Dave was concerning 5.25" DD formats, where I
use 5x1024 byte (or 10x512, if necessary). Dave argued to put one more 512
byte sector in the resulting gap4 (possible only with 5x1024), which I
strictly claimed (and still claim) ILLEGAL.

For those who still do not know about how to reach maximum LEGAL capacity,
and to end the rumours about my format definitions, here are some facts:

3.5" and 5.25" DD:   5x 1024 per side (200/400/800k)
5.25" HD and 8" DD:  9x 1024 per side (1440k)
3.5" HD:          11x 1024 per side (1760k)
All my formats have zero offset tracks (thanks to CP/M-Plus), so the above
capacities are NET.

Tilmann Reh            tilmann@mcshh.hanse.de
                       tilmann.reh@hrz.uni-siegen.dbp.de