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

Another good source of information on the IWM is the patent issued to Wozniak. Go to Delphion.com and you should be able to dig up the patent and order a .pdf of it for $3.00

Date: Thu, 27 Sep 2001 21:22:24 -0500 From: Bill Bradford <mrbill(a)mrbill.net> To: classiccmp(a)classiccmp.org Subject: Re: What's the volts for P70/P75 plamsa display on yours? Reply-to: classiccmp(a)classiccmp.org

I have two of these, minus the back panels, free for pickup in Austin, TX. One of them worked perfectly except for a bad HD, the other didnt power up at all - so I tried to swap the HD from the bad unit into the good one. When I got everything reassembled, neither will power up now... but I couldnt bring myself to throw them away. Sometime since then, the back panels have been lost. Keyboards and everything though... so let me know if anybody wants them. The screen on the "good" unit was absolutely beautiful when it worked. Bill

IWM refers to the "Integrated Woz Machine" if I remember correctly (I'm an Atari Historian, not an Apple Historian) Tom Owad could probably answer more correctly. Apple did a wonderful job at making a system not only flexible and efficient for disk drive access for a personal computer, but made it cheap, really unlocking the ability for the average user to finally have a decent storage medium that was fast and reliable.