Re: Apple2 disk controller questions

[CUTblakeney@home.com (Jeff Blakeney)]

On Thu, 08 Jul 1999 12:53:32 GMT, sales@mainlinebbs.com (John H.
Guillory) wrote:

>In fact, my Commodore FD-2000 uses MFM as its primary mode of
>operation, and gets 800k when in 1581 emulation, or using a
>double-density disk, and uses 1.6megs when in high-density, just like
>the mac.  The 1571, unlike the FD-2000, 1581, and 1541 can read both
>GCR and MFM diskettes, which is why I'd like to one day try to get the
>directory layout, etc. on an Apple diskette, and  see if the commodore
>could read it.

I keep looking in the thrift stores and such hoping to find a 1571
(and a 1581 or FD-2000 for that matter) but haven't had any luck yet.
I'd like to play with one myself.

>I have a
>question for the guru's out there... When you format a disk, what does
>the 1:2 and 1:4 mean?

That is the interleave of the sectors. 1:2 means that the sequences of
sectors uses every second sector and 1:4 means every fourth sector is
used.

For example a track with 16 sectors on a 1:2 interleave disk would
physically have the sectors order like so:

     1 9 2 10 3 11 4 12 5 13 6 14 7 15 8 16

and a track with 16 sectors on a 1:4 interleave formatted disk would
physically have the sectors ordered like so:

     1 5 9 13 2 6 10 14 3 7 11 15 4 8 12 16

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