[Coco] HD floppy controller update: success!
jcewy at swbell.net
Sat Jul 5 16:47:04 EDT 2008
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.
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.
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