>> QD is a misnomer, it really means DSDD 80-track, and the figure of 720K
>> relates to 9 sectors per track, 512 bytes per sector.
>
> QD was 96tpi TWO SIDED. There were two formats, 720k and 780k.
Come on, Allison, read the message before hitting the shift key. He said two
sided (embedded in the word "DSDD"). Some (Wabash?) QD disks I saw were
labelled "96/100 tpi 77/80 track" or words to that effect.
As for the two sided bit, try telling that to a Commodore 8050! This drive got
500k onto one side of a QD disk and ignored the other completely. I forget the
format, but the number of sectors increased towards the outside edge of the
disk...
> There were three basic soft sector medias, 35track (small window for
> head), 40 track (larger window) and the 600o 1.2mb. Obviously there were
> flavors of single and two side good media. Most large window was two
> sides good and worked in everything save for the odd 1.2mb drives.
Eh? What about QD? Which was that? It wasn't 35 or 40 track, but 77 or 80.
Given the Wabash label quoted above, can you confirm absolutely that the number
of tracks was a variation in head window?
Philip.
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Received on Mon Oct 04 1999 - 08:53:24 BST