Re: Poor-man's Catweasel

["Michael J. Mahon" <mjmahon@aol.com>]

mwillegal wrote:
> I'm pretty far along on a "smart" version for DIsk ][ drives,
> formatted in DOS 3.3 format.
> http://www.willegal.net/appleii/appleii-disk-int.htm.
>
> Note that properly formatting a disk and/or writing to individual
> sectors on a disk demands knowing and decoding the disk format on the
> fly.

Mike, on your web page you wrote:

>There is one final thing I need to do before actually testing out
>this write sector function.  That is to study the precise spacing
>between the end of the sector header and the sector data in Apple's
>RWTS.  I'll adjust my code to match as closely as possible.

and:

>[I] have found that 2nd sector on a track can't be found after writing
>sector 0 data. There is some special handling of sector zero in Apple's
>RWTS format function.   I'm in process of figuring out how that affects
>the sector 0 to sector 1 spacing.

When writing a sector, writing of sync nibbles should begin as soon as
the epilog of the address is complete.  (In fact, the second epilog
nibble is clobbered because of too little delay during formatting.)

So allow enough time to read the clobbered nibble, then start writing
several (6-8?) sync nibbles before the data header.

The object is to keep the data as close as possible to the address
field so that it doesn't overwrite too many sync nibbles leading into
the next address field--which is what I think is clobbering the next
sector after a write to sector 0.

-michael

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