[Coco] Why not 5.25 with XP?

David golgotha at toughguy.net
Tue Aug 22 19:58:38 EDT 2006

Hi Phil, thanks for the reply

Not being overly-techy when it comes to disk structures, etc..

Would it be possible to read two 256 byte (coco) sectors as one 512 byte 
sectors, and decode in software?

When writing out, you'd need to first read in the 512 bytes, modify the 
sector(s) as required, then write out as a 512 byte block.

Although this is double-handling, with smart use of software buffering 
etc it would work well.. as long as the hardware can be fooled into 
playing along

Of course, I'm probably not only barking up the wrong tree, but in the 
wrong yard altogether

Any thoughts?

- David

Phill Harvey-Smith wrote:
> David wrote:
>> Hi all,
>> I remember somebody mentioning *ages* ago that it's not possible to 
>> use Coco disks in a 5.25 drive while running XP
> This is true, infact XP won't even let you format a double density PC 
> format disk, though it will read and write them, if already formatted.
>> I seem to recall there was a technical explanation given relating to 
>> hard-coded sector sizes or somesuch which was incompatable with the 
>> coco disk structure
> That would appear to be correct, the XP (and probably the Win NT, 2000 
> & 2003 also), disk driver only appears to be able to read disk sectors 
> of 512 bytes as standard on the PC, for example I was able to read 
> Sinclair QL disks which also use 512 byte sectors but not CoCo or 
> Dragon disks, both of whicvh use 256 byte sectors.
> There is a custom written closed source (but free registeration) disk 
> driver that will read amongst other things CoCo disks....but I forget 
> the URL off the top of my head, it was discussed not so long ago here, 
> so may be worth searching the archives.
>> Is anyone able to shed any light on this, as if the problem is what I 
>> barely-remember it is, I may have a possible solution...
> That would indeed be cool. Though I have to admit I do most of my no 
> native disk reading under Linux, as I personally find it more 
> flexible, for this sort of thing. There's also Anadisk, which can make 
> disk images, though that only works under DOS/Win95/98/Me, you cold 
> run it from a boot disk tho....
> Phill.

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