Good description of Apple ][ disk controller

[Vintage Computer Festival]

On Wed, 23 Mar 2005, Eric J Korpela wrote:

> > There are no clock bits.  That's the whole point of GCR.
>
> Either that or they read the patent application....   In the patent,
> Woz describes the (13 sector) nybble format as being interleaved data
> and clock bits, with the clock bits all set to 1.  While this has a
> different meaning than clock bits in an [M]FM controller, you can
> still think of them as clock bits.  I would assume the patent text is
> an accurate description of what Woz said he designed.

I haven't had a chance to read the patent yet but this description might
be, shall we say, a "figurative" description of what's going on at the
physical level?

Everything I know so far would preclude the possibility of there being
clock bits interleaved with the data bits, as Eric confirmed.  Otherwise,
there would be no point to the GCR method.

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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