[Coco] HD floppy controller update: success!

[Joel Ewy]

Chuck Youse wrote:

> On Sat, 2008-07-05 at 11:35 -0500, Joel Ewy wrote:

>   

>> Hey Chuck,  this is good stuff you're working on.

>>

>> IMHO, I think a High Density CoCo OS-9 disk should be formatted the same

>> as an MM/1 HD floppy.  The MM/1 uses the WD37C65, and 33 256-byte

>> sectors per track.  I don't have any info immediately at hand about gap

>> length.  In the MM/1 technical manual the "rates" parameter to dmode is

>> $10.  Perhaps this is passed directly to the FDC, and the 37C65

>> datasheet might give more specific info.

>>     

>

> Hmm, that's a rather odd format.  Is that a 5.25" HD floppy or 3.5"?

>

>   

This is 3.5"

> The only problem I have with this is the fact that Linux freaks out when

> you have a combination of 256-byte sectors and an odd number of sectors

> per track.  And really that only concerns me because one of the main

> advantages to having this controller is that it makes transport of files

> between systems much simpler.

>   

And that's a good reason.

> But really, it's not set in stone; it's all driver-driven at that point.

> Even differing device descriptors under OS-9 should give you the

> MM/1<->Coco enjoyment you want.

>

> C.

>

>   

True enough.  Dmode to the rescue.  I remember having several sets of
device descriptors hanging around on the CoCo, and even an extra driver
that ran the Disto SCII in halt-mode so I could read in 512-byte sectors
for the 'rsdos' utility.  I had a 'di' descriptor for reading IBM
formatted disks (as they still would have been called in those days.). 
So I could 'rsdos -get -raw /di /h0 filename' or whatever.

JCE


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