Re: 3.5" drives & daisy-chaining DuoDisks

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <pierre_houston-1902962344260001@nightshade.gdt.com>,
Pierre Houston <pierre_houston@gdt.com> wrote:
> I'm need more info on 3.5" drives & controller cards for a //e, and
> the practicalities of daisy-chaining a DuoDisk unit (its possible 
> right??).

In the right circumstances, yes.

> So I'm full of questions:
> 
> I understand that the newest controller card will handle HD 3.5" drives,
> but is it true that none of those drives can daisy-chain to a DuoDisk (or
> something like that)?

Not exactly.  The SuperDrive controller card only supports 3.5"
drives, so you wouldn't be able to daisy-chain a DuoDisk off any drive
connected to it.

The only disk ports that support both 3.5" and 5.25" drives are the
IIc, IIc+ and IIgs.  In the latter two cases, you could connect an
external 3.5" drive with a daisy-chained DuoDisk.  (You might be able
to do this on a IIc, but you would only be able to access one drive,
and I'm not sure whether the second one would behave itself.)

The Universal Disk Controller card (from Central Point Software) also
supports a mixture of 3.5" and 5.25" drives, but you can only connect
two drives to it (two of either type, or one of each type).

> With that controller card, what flavours of 3.5" drives can and can't
> I use? 

The SuperDrive card supports the Apple 3.5 Drive, SuperDrive and
UniDisk 3.5.  You can connect a maximum of two Apple 3.5 or SuperDrives
(two of the same type or one of each).  It is possible to connect more
than two drives by adding UniDisk 3.5s (connected AFTER the Apple
3.5 Drives or SuperDrives).  The absolute maximum is probably four
drives (four UniDisk 3.5s, one Apple 3.5/SuperDrive and three UniDisk
3.5s, or two Apple 3.5/SuperDrive and two UniDisk 3.5s) due to signal
loading limits.

You probably cannot use Macintosh 400K or 800K drives with this card
(they don't work with the IIgs disk port).  Third-party drives should
work, provided they also work on the IIgs disk port and are compatible
with the Apple 3.5 or SuperDrive.

BTW, the card's official name is the "Apple II 3.5 Disk Controller Card".

> If I'm not able to get one of those newer cards (i understand they're hard
> to find) what other varieties of cards are there? What flavours of drives
> work with them?

The "Liron" card (official name "Apple II 3.5 Floppy Disk Drive
Interface Card", if I remember right) can be used in a IIe (and
possibly a II+).  It only supports the UniDisk 3.5.

The Universal Disk Controller (see above) supports the Apple 3.5
Drive, Macintosh 400K/800K drives and standard Apple II 5.25" drives
(it has D-19 connectors, so you would need an adaptor to use a Disk
][).  It doesn't support the UniDisk 3.5, and a SuperDrive will be
limited to accessing 400K/800K disks when used with this card.

> I read recently about cutting a resistor to make a daisy-chained DuoDisk
> more reliable? Was that only in regards to IIgs smartports, or should I
> pay attention to this matter also? Where can I get info on this mod? Also,
> do I need a different cable or is the connection to a daisy-chainable
> drive the same as to an original DuoDisk controller?

The connection is the same - on the IIgs, for example, one or two
UniDisk 5.25s can be daisy chained after the last 3.5" drive.  The
DuoDisk can be connected in the same way.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand