🚀 go-pugleaf

In article <YePUNYK00WB5ECXq4i@andrew.cmu.edu> rg20+@andrew.cmu.edu (Rick  
Stanley Francis) writes:
> Your post's title was a bit misleading, after all you only seem to
> want to emulate the Amiga's file system.

[ suggests using MS-DOS disks ]

I do that now.  I don't have a floppy drive on my NeXT, so I use
a Sparc's.

You probably could make the NeXT drive do the trick.  An
MS-DOS DD disk is 80 cylinders, 9 sectors per.  An Amiga
disk is 80 cylinders and 11 sectors per.  If you can coax the
drive into doing that, you'd just have to implement the
filesystem, which shouldn't be much harder than the
MS-DOS one was.

(An Amiga drive can do either as well as more bizarre
stuff.)

ab

In article <54889@mentor.cc.purdue.edu>, ab@nova.cc.purdue.edu (Allen B) writes:
|> 
|> You probably could make the NeXT drive do the trick.  An
|> MS-DOS DD disk is 80 cylinders, 9 sectors per.  An Amiga
|> disk is 80 cylinders and 11 sectors per.  If you can coax the
|> drive into doing that, you'd just have to implement the
|> filesystem, which shouldn't be much harder than the
|> MS-DOS one was.
|> 
|> (An Amiga drive can do either as well as more bizarre
|> stuff.)
|> 
Yeah, an Amiga drive can do very many tricks, especially using a non MFM coding
sceme - it's Commodore's own GCR format. So you won't be able to even read
a single sector with a 'standard' disc controller.

Uli

In article <1992Jul28.114640.9099@infoserver.th-darmstadt.de> uli@aida.intellektik.informatik.th-darmstadt.de (Ulrich Grepel) writes:
>In article <54889@mentor.cc.purdue.edu>, ab@nova.cc.purdue.edu (Allen B) writes:
>|>
>|> (An Amiga drive can do either as well as more bizarre
>|> stuff.)
>|>
>Yeah, an Amiga drive can do very many tricks, especially using a non MFM coding
>sceme - it's Commodore's own GCR format. So you won't be able to even read
>a single sector with a 'standard' disc controller.
>
>Uli

    Even though the Amiga's controller can stuff raw bits, the Amiga uses a
    standard MFM encoding.  The difference is that the Amiga reads and
    writes whole tracks at a time and therefore needs no gaps between
    sectors, thus getting 11 sectors/track instead of 9.

					    -Matt

--

    Matthew Dillon	    dillon@Overload.Berkeley.CA.US
    891 Regal Rd.	    uunet.uu.net!overload!dillon
    Berkeley, Ca. 94708     ham: KC6LVW (no mail drop)
    USA

dillon@overload.Berkeley.CA.US (Matthew Dillon) writes:
>>Uli
>
>    Even though the Amiga's controller can stuff raw bits, the Amiga uses a
>    standard MFM encoding.  The difference is that the Amiga reads and
>    writes whole tracks at a time and therefore needs no gaps between
>    sectors, thus getting 11 sectors/track instead of 9.
>
>					    -Matt
>

Yes, that's what it _usually_ does (its native format).  But if you look
at the tech docs, you'll see that it can also do group code, a fact
used to great advantage by Mac Emulators (with some additional hardware
to do the disc speed.)  I never tried it out myself, but I would have
loved to do a Apple DOS 3.3 compatible file system in 68K Assembler :-)

Marcel