Re: Apple II 3.5" Controller and SuperDrive problems...

[spec@vax2.concordia.ca (Mitchell Spector)]

In article dempson@actrix.gen.nz (David Empson) writes...

>3. For the UniDisk 3.5 to work on the IIc, the IIc must have ROM version
>0, 3 or 4.  ROM version 255 must be upgraded.

    It also functions with ROM version 5--the Apple IIc Plus.

>4. I don't think the UniDisk 3.5 is supported by the Universal Disk
>Controller.  (I haven't verified this myself, but I've heard it from
>others several times.)

    I believe certain versions of the UDC board supported it, while
others did not due to either firmware or hardware changes. I recall
it being the former based on a discussion in this group awhile ago.

>5. No mention of the IIc+, which has a built-in 3.5 drive and will
>support the Apple 3.5 Drive, and can use both drives in a DuoDisk
>(otherwise matches a IIc).

    As mentioned above, it also supports the UniDisk 3.5 drive, not
too mention the Apple SuperDrive in 800K emulation mode (of course
neither type of drive deserves to be wasted on a IIc Plus when it
works with the Apple 3.5 just fine).

>7. In some cases the DuoDisk has problems on the IIgs, and requires a
>hardware modification.  (I don't have the details handy.)

    I still stick to the belief the ROM 3 IIgs is not compatible with
the DuoDisk, based on my own personal experience and Apple discussion
notes (in the Apple Tech Info Library) stating compatibility issues
are a problem. Stephen Buggie claims his DuoDisk works from his ROM 3
IIgs, although I'm not sure if he modified the drive or not.

    The hardware modification (involved clipping some components off
the analog board) was to reduce power consumption so it could work
when daisy-chained from the IIgs's disk port. Apple came up with the
fix well before the ROM 3 motherboard was even conceived and offered
no solution years later--except to use a slot based controller card
or avoid using the drive altogether.

>11. No mention of the Applied Engineering 3.5" drives.  The 800K one is
>basically compatible with the Apple 3.5 Drive, and there is also a high
>density one (1600K format) which only works on the IIgs built-in port,
>and then only with a special driver.  (I believe this is the case - can
>anyone else confirm or deny?)

    From what I recall, the so-called 1600K AE FDHD 3.5 drive was
a SuperDrive clone with a lesser version of the Sony mechanism.
With AE's GS/OS driver, you could use a proprietary 1.6 MB format
on the GS (at least for data storage, don't think it could boot).

    There may have been extra circurity inside, as I'm not so sure
you could connect an official Apple SuperDrive to the back of the
IIgs and read/write 1600K floppies using AE's GS/OS driver. I also
remember AE selling the same drive to the Amiga community with a
special driver to do a proprietary 1.7 MB format.

Mitchell Spector
spec@vax2.concordia.ca