1237e20007c3
tech



Hello Viktor - 

CA>>> That may be a factor but I'm not saying a drive that
CA>>> won't do an extended format is 'bad' or 'broken', only
CA>>> that certain drives did not allow the head to travel
CA>>> beyond the accepted 'last track' position while other
CA>>> drives did. :-) 

DD>> Ah - I had an idea that the number of tracks was the same,
DD>> and they crammed more sectors per track.... 

VP> The basic formats for 3.5" floppies are: 360k (1 Side, 80
VP> Tracks, 9 Sectors/Track), 720k (2s 80t 9s/t), 1.44m (2s 80t
VP> 18s/t) and 2.88 (2s 80t 36s/t) - all of the extended
VP> formats are based on those 4 (actually the last 3 - 360k
VP> didn't have any extended formats). 

Yes, 360K does have one out to more than 400K. :-)

VP> Mostly it went by increasing sectors/track like this: For
VP> 720k - 10 (800k), 13 (1.04m) and 14 (1.12m). For 1.44m - 20
VP> (1.6m), 22 (1.76m), 23 (1.84m) and 24 (1.92m) For 2.88m -
VP> 39 (3.12m), 40 (3.20m), 44 (3.52m) and 48 (3.84m) 

VP> There were also attempts to increase capacity by increasing
VP> the number of tracks, but those never became too popular
VP> because of problems with compatebility and reliability: For
VP> 720k 10s/t - 82 (820k) and 83 (830k) tracks For 1.44 21s/t
VP> - 82 (1.72) and 83 (1.74) tracks 

1.44 meg floppies can go as high as 1.9 meg, I have some here
somewhere but haven't tried reading them lately (the machine I
used for the format has long since died and I think DOS requires
a TSR to read them). :-\

>
>        ,                          ,
>      o/      Charles.Angelich      \o       ,
>       __o/
>     / >          USA, MI           < \   __\__
 

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