Apple ][ disk controller state machine

Thanks, dq. I have seen that doc, but it speaks mainly of the 3.5 drive, which had several enhancements not available on the 5.25 drive. Was the Apple ][ controller sufficiently similar to the IIgs and progeny that this documentation is appropriate for it also? I've never heard the Apple ][ controller chip referred to as 'IWM' -- is that my ignorance, or was the chip renamed, or are they (maybe slightly) different beasts? - Sean Douglas Quebbeman 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? > > From: > http://www.mac.linux-m68k.org/devel/iwm.php > > : ======================= > : Accessing IWM Registers > : ======================= > : The IWM chip has several internal registers available to programs. > : Access to these registers is controlled by the Q6 and Q7 switches. > : > : +=====+=====+=======================================+ > : | Q6 | Q7 | Register | > : +=====+=====+=======================================+ > : | off | off | Read data register | > : +-----+-----+---------------------------------------+ > : | off | on | Read handshake register | > : +-----+-----+---------------------------------------+ > : | on | off | Read status register | > : +-----+-----+---------------------------------------+ > : | on | on | Write mode register (if drive is off) | > : | | | data register (if drive is on) | > : +-----+-----+---------------------------------------+ > : > : The mode register is a write-only register containing several flag

> : which control various features if the IWM. To access it, turn off the > : drive (by accessing ENABLE), turn on Q6 and Q7, and write to any > : odd-numbered address in the $C0E0...$C0EF range. > > hth, > -dq