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