[Coco] Re: Oddball disk format question

[Robert Gault]

Torsten Dittel wrote:


> The more I think about it the more I'm sure the sequence you're

> describing could be created using a "killer" bit sequence. I have to

> think about how it worked (has to do with MFM coding). Just so far: What

> you're reading with READTRACK is *NOT* what was written with WRITETRACK.

> Some of the bytes are "faked" by these killer bits which are interpreted

> as a syncing signal due to a "bug" of the controller (I think it's on

> purpose the READTRACK doesn't work properly to allow copy protection

> schemes).

> 

> Torsten

> 

> 


I know that some of the bytes are faked. I've stated how the 248 sector 
number can be created and the CRC for the track ID can be inserted 
manually. I just don't see how the data was created to include $A1, $F5, 
$F6, and $F7.