Subject: proposal for MI floppy formatting
To: tech-kern <tech-kern@NetBSD.ORG>
From: Hauke Fath <>
List: tech-kern
Date: 12/01/1996 23:07:23
>   MI floppy formatting proposal:
>   $Id: proposal,v 1.2 1996/11/16 17:02:32 jtk Exp $
>   #define FDFORMAT_VERSION 19961116
>   struct fdformat_parms {
>   /* list of items taken from i386 formatting glop (NEC 765);
>      should be made the union of support needed for other devices. */
>       int fdformat_version;	/* rev this when needed; write drivers to
>				      allow forward compatibility, please,
>				      and add elements to the end of the
>				      structure */
>       int sector_shift;
>       int nbps;			/* number of bytes per sector */
>       int ncyl;			/* number of cylinders */
>       int nspt;			/* sectors per track */
>       int ntrk;			/* number of heads/tracks per cyl */
>       int stepspercyl;		/* steps per cylinder */
>       int gaplen;			/* formatting gap length */
>       int fillbyte;			/* formatting fill byte */
>       int xfer_rate;			/* in bits per second; driver
>					      must convert */
>   };


a late annotation, as I follow the list through the digests which are two
weeks late, as always. -- I have my hands on a mac68k floppy driver.

You would want to allow for a variable number of sectors per track (ZBR) if
you want to pull the mac68k GCR format into your MI boat.

With Macintosh 68k hardware, formatting a track is essentially setting
things up in a mem buffer and writing it to disk, much like the Amiga does

As the physical structure of the track is all different from vanilla MFM
stuff, most of the record fields in the above data structure are
meaningless for GCR (nspt, gaplen, fillbyte, xfer_rate), and others may
additionally be required.

I haven't got much time now - if you're interested, I hope to come up with
more details before next year.


"If the designers of X built cars, there would be no fewer than five
steering wheels hidden about the cockpit, none of which follow the same
principles - but you'd be able to shift gears with your car stereo.
Useful feature, that."    ( in