Good description of Apple ][ disk controller

[Mike Cesari]

On Mar 21, 2005, at 10:19 AM, Vintage Computer Festival wrote:

>
> I am pretty surprised that I can't find any good technical 
> descriptions of
> the Apple ][ disk controller.  It's not in the DOS manual and, come to
> think of it, I can't think of any publication Apple came out with that
> describes it.  I wonder why this is?
>
> Does anyone have any good suggestions for reference material on this
> subject?  I've got Beneath Apple DOS, which is of course excellent, and
> the Bag of Tricks manual (which rehashes a lot of what's in BAD), but
> nothing outside of those really describes the disk controller 
> circuitry at
> an even lower level.  I want to know what's going on in the PROMs, and 
> why
> the certain rules of encoding data are why they are (i.e. first bit of
> every disk byte must be set, no more than one set of consecutive zeros 
> in
> any byte, etc.)
>
> -- 
>

Check out Aaron Heiss' Apple ][ page. Especially the Apple ][ tech 
notes (posted
with Apple's permission). You'll have to dig for the disk controller 
info.

http://web.pdx.edu/~heiss/

Mike