Re: Disk II Half - Quarter Tracks

["RedskullDC" <RDC@oz.org>]

Hi Bryan,

"Bryan Parkoff" <nospam@nospam.com> wrote in message 
news:45cbe9b7$0$28149$4c368faf@roadrunner.com...
>    Can you write the bit stream?  Like this AA AB 96 96 96 .... 96 96 96 
> FC FC on Track 1 without address field and data field.  AA AB is the start 
> of bit stream.  FC FC is the end of the bit stream.  Try to read all bytes 
> on Track 1 and use loop to count the number of byte value 96.
>    Try to write by replacing from 96 to 97 on Track 1.25.  9A on Track 
> 1.50.  9B on Track 1.75 and 9C on Track 2.  Did it tell you when you 
> attempt to read and count the byte values on Track 1, Track 1.25, and 
> Track 1.50. Did Track 1, Track 1.25, and Track 1.50 report to be 9A?  Did 
> Track 1.75 report 9B?
>    It is evident that Track 1.50 has overwritten 9A to replace 96 and 97 
> on Track 1 and Track 1.25 because the arm head is too width.  Track 1.75 
> and Track 2 are not overwritten.
>    Did you have done your experiment?
>
> Bryan Parkoff
>

I did once experiment with the track widths to see what could be achieved.

Using a stock standard Disk][, writing on every half track proved to be 
unreliable.
Sometimes the adjoining track's data would be garbled, other times not.
I didn't do exhaustive testing of the bit patterns on adjoining tracks (as 
you suggest)
to see what effect it had.

Writing tracks at 3/4 intervals ( 1, 1.75, 2.5, 3.25 etc.) did seem reliable 
enough
however. It didn't appear to have any effect on the data that was already 
recorded
on the adjoing tracks.

The DOS3.3 track stepping routines would need to be modified to support 3/4
track spacing, but it would be possible to easily gain an extra 50% storage 
capacity
on a disk][ this way.

Differing results may be obtained using different disk][ drives, as I have 
no idea of
the manufacturing tolerances of the read/write head widths.

Red