Re: sys/dev/isa/fd.c FDUNIT/FDTYPE

[jnemeth%victoria.tc.ca@localhost (John Nemeth)]

On Sep 25,  5:05pm, Hauke Fath wrote:
} At 10:53 Uhr -0700 5.5.2011, John Nemeth wrote:
} >} land (and my current intent is only to have the content of some four
} >} shoeboxes full of (mostly ten-sector) Atari floppies more readily
} >
} >     These are actually readable on a standard PC style floppy drive?
} 
} That's "Atari ST" (68k) standard MFM, as opposed to the 6502 based
} predecessors, which IIRC were closer to Apple II and Commodore formats. The
} ST shipped with a 68k MSDOS 2.0 clone.

     Ah, okay.

} Because of the WD1772 controller's properties, and on certain floppy
} drives, people managed to squeeze up to 12 sectors on a track with
} custom-made formatters that reduced the inter-sector gaps.

     The sparc{,64} floppy controller chip is basically a PC floppy
controller chip.  The main difference is that SBus based machines don't
support PC style DMA, so the chips are configured for pseudo-DMA where
you read/write data one byte at a time inside an interrupt handler.

} (who wrote another "late NetBSD floppy driver" for the Macintosh IWM)

     That must have been fun.  As I recall, this was basically the
Apple ][ disk controller squished into one chip. It was hard to call
that thing a disk controller since it wasn't much more then a TTL
driver and a shift register.

     My first experience with "operating systems" was basically taking
a printout of a disassembly of Apple DOS 3.3, figuring out how it
works, and documenting the entire thing, then mangling it to do various
tricks.  I wonder where that printout is?  I probably still have it
somewhere.

}-- End of excerpt from Hauke Fath