Apple ][ disk controller state machine

From: Sean Gugler <>
Date: Wed Sep 5 21:01:17 2001

Tony, thanks for checking on this!

"Beneath Apple ProDOS" is probably what I want, then. I've never seen
either book, but I heard the second offered some recap and some fresh
material that was also useful to DOS 3.3 -- possibly the state machine
flowchart was among the fresh material, not recap.

          - Sean
Sean Gugler ("Dr. Guz")
"This quote's just six words long."
Tony Duell wrote:
> >
> > Until I get my hands on a copy of the venerable "Beneath Apple Dos"
> > is there anyone who can point me to an online resource describing the
> > Apple ][ disk controller P6 ROM state machine?  The exact uses
> > for the Q6 and Q7 switches ($C0EC-$C0EF)?  Or would be willing to
> > summarize from the mighty tome for me?
> I've just pulled out my copy of 'Beneath Apple DOS', and the information
> you need doesn't seem to be in there. There's very little about the disk
> hardware at all -- it assumes you'll at least use the standard routines
> to read/write bytes on the disk.
> >From the schematics in the Apple DOS manual, it appears that Q7 is
> inverted and turned into the write gate/ line to the disk drive. So
> presumanly Q7 is a write enable input (it does also go to the state
> machine PROM and I guess it sets up the state machine for writing).
> Q6 only goes to the state machine, so I have no idea what it's for (I've
> not analysed the state machine -- yet!)
> -tony
Received on Wed Sep 05 2001 - 21:01:17 BST

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