[comp.sys.mac] Geometry of Apple SC80

aad@stpstn.UUCP (Anthony A. Datri) (03/16/89)

I need the geometry for the 80 meg Quantum disk in an Apple 80SC drive.
Any help appreciated.


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Anthony A. Datri @SysAdmin(Stepstone Corporation) aad@stepstone.com stpstn!aad

kaufman@polya.Stanford.EDU (Marc T. Kaufman) (03/17/89)

In article <3083@stpstn.UUCP> aad@stepstone.com (Anthony A. Datri) writes:

>I need the geometry for the 80 meg Quantum disk in an Apple 80SC drive.
>Any help appreciated.

There are $262D2 = 156370 sectors on the HD80.  This is 19 x 10 x 823.
I would make a first guess that this represents 823 cylinders, 10 heads, and
19 sectors per track. (other factorizations may be possible).

Marc Kaufman (kaufman@polya.stanford.edu)

cander@unisoft.UUCP (Charles Anderson) (03/21/89)

From article <7772@polya.Stanford.EDU>, by kaufman@polya.Stanford.EDU (Marc T. Kaufman):
> In article <3083@stpstn.UUCP> aad@stepstone.com (Anthony A. Datri) writes:
>>I need the geometry for the 80 meg Quantum disk in an Apple 80SC drive.
>>Any help appreciated.
> There are $262D2 = 156370 sectors on the HD80.  This is 19 x 10 x 823.
> I would make a first guess that this represents 823 cylinders, 10 heads, and
> 19 sectors per track. (other factorizations may be possible).

Close, but not quite. There are 823 cylinders, 32 sectors per track, 6
heads, two alternate sectors per cylinder.  Thus, there are 190 usable
sectors per cylinder.

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Charles.
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