Re: Apple ][ plus 13 sector! Problems...

["Bill Garber" <willy46pa@comcast DOT net>]

"David Empson" <dempson@actrix.gen.nz> wrote in message
1gh55xq.ad72g01oor7z2N%dempson@actrix.gen.nz">news:1gh55xq.ad72g01oor7z2N%dempson@actrix.gen.nz...
: "Bill Garber" <willy46pa@comcast DOT net> wrote:
:
: > Thank you David. I really must take some time
: > and read through all these books. After all,
: > I did buy them to learn from. What programs
: > can I use to convert a 13 sector disk image to
: > a real disk?
:
: No idea.  I haven't done anything signficant with
: emulators.  I only use the real thing. :)

You may assume I mean Emulated and/or Real when I am
asking questions and answer accordingly.  Thanks.

: > From what you wrote above the 16 sector controller should be
: > able to still write one?
:
: Yes.  The 16-sector controller (and the 13-sector one)
: can write anything, even disk bytes which can't be read
: back by the same controller: any 8-bit data pattern is
: possible, but if the written byte doesn't follow the
: rules, it won't read back reliably (or at all).  You
: can even write mistimed bytes, by waiting longer than
: 32 microseconds between writes.  (I'm not sure what
: would happen if you waited less than 32 microseconds -
: probably get a partial byte followed by the next byte.)

The Beneath Apple DOS book is fairly adamant about waiting
for at least the 32 uS, so I'd say you are probably right
about that.

: Copy protection techniques have been known to pull
: these sort of tricks, and use other tricks such as
: timing measurement to determine whether the disk
: has been written with the correct special rules.