[Coco] Imaging MM/1 Floppy Disks

[Joel Ewy]

On 01/01/2016 09:37 PM, Joel Ewy wrote:
> ...
>
> I notice that every time I try to read a high density MM/1 floppy, 
> formatted to either 33 or 37 sectors per track, dd goes through the 
> motions, and creates an image file, but also gives an I/O error at the 
> end.  Also, it consistently reports that it has copied 160 sectors 
> fewer than the disk format should have -- with either 33 or 37 spt, 
> and apparently with soffs=0 or soffs=1.  160 sectors is 2 sectors per 
> track on an 80 track disk.
>
> JCE
>
Really, that's 1 sector per track per disk side.  I used ded to write 
the sector number in each sector from 30-80.  Sectors 36 and 73 are 
missing.  This is using a disk formatted with soffs=1.  And indeed 
sector 1 is present in the image file.  Really the numbering is off by 
one because ded still numbers the sectors starting with 0, which just 
means that the 37th and 74th sectors were not read by dd.  But why?

JCE