Unix floppy disk formats (was: Backups of Distibution Floppies)

[Frank Bicknell]

In article <241 at vector.Dallas.TX.US>
	chip at vector.Dallas.TX.US (Chip Rosenthal) writes:

> In article <752 at mccc.UUCP> pjh at mccc.UUCP (Pete Holsberg) writes:
> > [...cte] we were both wondering how to make backups of the
> > distribution floppy disks?  Can you use DISKCOPY or are they
> > *NIX-formatted disks?  [etc...] 
> 
> There is no such thing as a "unix-formatted" disk.
> [much interesting information about formatting deleted]

Your statements are true, but there are little details about
the usage of that formatting which differ from unix to unix.

It depends on what unix you're talking about.  Some unixes,
such as AT&T (3b2,3b1) do something weird with the first
track or two.  While there was no difference in the
formatting of those tracks, they decided to skip them and
reserve them for booting even when you are placing a tar
image on the disk!  AT&T are not the only folks to do this:
I've run across a BSD-based Unix which does the same sort of
thing.  BTW...  it's common to find 640K (96ds8) on other
unix floppies.  

We are fortunate that the kind folks at SCO decided to not
do such monkey business and chose the straightforward
approach when using the disk for a non-bootable floppy.
They were even forward-thinking enough to allow almost
complete flexibility with the floppy drive (8,9,15 spt,
48,96,135 tpi, even ds,ss!  Anyone still use single-sided
floppy disks? :) ).  

So, between using the flexibility of the floppy device
driver and the ability to skip tracks/sectors/whatever with
the 'seek/skip' options of 'dd', I've found I've been able
to read other unix's floppies very nicely with SCO.
Unfortunately, the reverse is not true: I don't know how to
read a 48ds9 (360K) floppy on one of those other machines,
for example, and it's mighty inconvenient (though I presume
possible using the raw device and 'dd') to create or read a
tar disk which begins at track 0.  

And now a question: why is it that floppy operations are so
incredibly slow under unix.  SCO and AT&T are both bad about
this.  Do something on the floppy drive and you may as else go
to lunch while it's chugging along.  A 3b2 (older models, at
least) takes about two minutes to read or write one 80-track
floppy!!!  That's about 1.5 seconds a track.  It's academic, of
course... I haven't used the floppy as the swap device in some
time now... 
-- 
Frank Bicknell
UniSource; 1405 Main St, Ste 709; Sarasota, FL 34236
killer!usource!frankb || frankb at usource.UUCP