[G5] A Stupid Question..

[Zane H. Healy]

Pat wrote:
> On Feb 18, 2005, at 6:02 PM, Valerie Maples wrote:
> 
> > Be careful!  The external floppy drives I have found cannot read the DD
> > disks, only HD.  If someone finds an external USB floppy drive that 
> > reads
> > both, please let me know.

> Help again...what is the difference?  What happens if they are the 
> wrong kind?  And how do I tell the difference?

If I remember correctly, the Lisa 2's, Apple //C+'s, and the original Mac's
all used SSDD floppies (Single-Sided, Double Density), from the Mac SE on
(including the Apple //gs) they either used DSDD (Double-Sided, Double
Density), or DSHD floppies (Double-Sided High Density).  Then from about the
Mac II on, all floppies were DSHD.  I can't remember exactly how much a SSDD
holds 360k makes sense, but I think it was 400k.  A DSDD is 720k, and a DSHD
is 1.44Mb.  Wait a minute, I might be mistaken, I think Mac's actaully wrote
DSDD floppies at 800k, which could explain why USB floppy drives apparently
can't handle them.  (I know PC's, Atari's, and IIRC Amiga's all wrote DSDD
at 720k).

Old 68k Mac's could handle Mac, ProDOS (Apple II) and PC (FAT) 3.5"
floppies.  I don't remember if the early PPC Mac's could read ProDOS
floppies, but I do know that the fastest way to read a floppy was a 68k Mac. 
When I bought my G4/450 AGP, while I was waiting on it, I imaged almost all
of my Mac floppies, and I ended up doing this on my 68k-based PowerBook 520c
rather than my PowerMac 8500/180, as it was far faster to do it on the old
slow PowerBook and copy it over 10Mbit ethernet to the 8500 (where I then
put them on CD-R).

The only Apple systems to use 5.25" were Apple //'s, and Lisa 1's used
"Twiggy" floppies.  No Apple system used 8" floppies.  And yes, I've used
everything mentioned above and some even more frightening storage devices
with the exception of the Twiggies :^)

Oh, and for other 3.5" floppies I don't remember ever seeing 2.88Mb floppies
on a Mac, but 21MB (I think that's the right size), or LS120 120MB
"floppies" are possible but only via a 3rd party external drive.

Confused yet?  Or just information overload :^)

		Zane