Re: cbm 1541 drive reading AppleIIe 5.25" disks?

[<K3027E7@ALIJKU11.BITNET>]

fox@feenix.metronet.com (Fuzzy Fox) writes:

>The 1541 recognizes 10 1-bits as a sync mark.  While 8 bits would be
>pushing it, it just might work.


  There can also be sequences of more than 10 1-bits on Apple II disks.
Data bytes are split into 6-bit groups. Each of them is stored as an
8-bit value, which can be $FF. Thus, in the worst case the complete
data section consists of 1-bits.
  Sync marks on Apple II disks consist of alternate 8 1-bits and
2 0-bits.

  So, some method of switching off the 1541 sync detection would be
necessary. And, as the 1541 does not recognize the Apple II sync marks,
it would not even read bytes at the correct bit position.

 If someone is still interested: I have found rather detailed information
about the Apple II disk format in an old German computer magazine
(mc 6/1983). Feel free to ask.


Richard Hable
k3027e7@edvz.uni-linz.ac.at