Re: CBM-900 floppy disk format/encoding

On 2011-10-23 02:03, MikeS wrote:
> Well, I still think it's highly unlikely that the CBM-900 would use
> totally incompatible 100TPI disk drives/format, but I suppose anything
> is possible.

I agree that following the standards of that time would be the right choise.

but when talking about Commodore I would expect anything - even the most 
irational choise. :-D

In a little week I'll be able to say more - I hope.

>
> If the Kryoflux can read the flux that would seem to suggest that you're
> on the right tracks ;-) and it just can't make sense of the actual layout.
>

I'm no expert - but I would guess that some kind of "flux" could be read 
out of the disk even out side the tracks ?

> But good luck!
>

Thanks :-)

> ----- Original Message ----- From: "Uffe Jakobsen" <uffe@uffe.org>
> To: <cbm-hackers@musoftware.de>
> Sent: Saturday, October 22, 2011 7:54 PM
> Subject: Re: CBM-900 floppy disk format/encoding
>
>
>>
>>
>> On 2011-10-22 18:01, MikeS wrote:
>>> I think we're all agreed that the SFD1001 uses the same format as the
>>> 8x50,
>>> namely DD, GCR, 100TPI, 500KB/side, and is essentially 1/2 of an 8250.
>>>
>>
>> Agree
>>
>>> But the question is what did the CBM-900 use, and I would think it much
>>> more
>>> likely that its 1.2MB UNIX disks would be industry-compatible HD disks
>>> instead of somehow squeezing an extra .2MB out of a DD disk that
>>> would not
>>> be compatible with anything at all.
>>>
>>> So I doubt that it was actually compatible with the SFD1001, but I'm
>>> just
>>> guessing. In any case, if no one comes up with a definitive answer, I'd
>>> suggest to the OP that he try using an HD drive and diskette and see
>>> whether
>>> it works.
>>>
>>
>> Given the fact that I've already tried dumping the disks with an 80
>> track drive (HD) - I'm leaning more to my own conclusion which is:
>>
>> I need to get hold of a 100 TPI floppy drive and try that with my
>> kryoflux.
>>
>> Thanks for your input - I'll keep the list updates on my progress.
>>
>> Since sources document that aprox 500 CBM-900 prototype units were
>> made I'd have expected that this list was the (only) right place to
>> hear about owners of CBM-900 systems - but it is never too late for
>> any of them to speak up :-)
>>
>> Thx
>>
>> /Uffe
>>
>>
>>> ----- Original Message ----- From: "Greg King" <greg.king4@verizon.net>
>>> To: <cbm-hackers@musoftware.de>
>>> Sent: Saturday, October 22, 2011 5:02 AM
>>> Subject: Re: CBM-900 floppy disk format/encoding
>>>
>>>
>>>> From: "William Levak"; on Sat., October 22, 2011; at 01:11 AM -0400
>>>>>
>>>>
>>>>> On Fri, 21 Oct 2011, Ed Johnson wrote:
>>>>>
>>>>> > I have a SFD 1001 and it used DS/DD diskettes, NOT HD (High Density)
>>>>> > diskettes.
>>>>>
>>>>> The drive mechanism on the SFD 1001 is a Quad Density drive,
>>>>> compatible with DD, but not HD.
>>>>
>>>> "Quad" was a marketting gimmick. It wasn't related to single- and
>>>> double-density. It meant that the track density, not the bit density,
>>>> was "doubled".
>>>>
>>>> The 4040 format is 48 Tracks Per Inch, while the 8050 format is 100
>>>> TPI.
>>>>
>>




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