[Coco] Dead (??) 5 1/4" drives

[Gregory Law]

Wikipedia is correct in that in in 5.25 inch disks QD represents quad 
density 720K.

Are you possibly thinking of the 3.5 inch ED (extended density) 2,880K 
disks?

On 3/8/2017 12:18:42 PM, "Gene Heskett" <gheskett at shentel.net> wrote:

>The wiki would be wrong. In 5.25 disks, DD meant its was surface
>formulated for a 250 kilobyte data rate, which the coco's controllers
>do.
>
>HD meant a 500 kilobaud data rate, and QD was an extremely fine grained
>coating formula, intended to be used on 1 megabaud data rate
>controllers. The 1200's were an early attempt at a 1440, on a 5.25"
>media at a 500 kilobaud data rate but with the disk speed turned up 
>from
>300 RPM to 360 RPM because that increase in disk surface velocity got
>the playback signal up out of the noise floor far enough to be usable.
>