Here is a patch to read 720K and 360K floppies. I think I saw someone
from Japan asking about it. To read/write 720K floppies use /dev/rfd1e
(if your 3.5" drive is drive 1), or /dev/rfd0e (if your 3.5" drive is drive 0).
The minor number of this device equals 4, which is the right index
into the fdtypes table.

Onno van der Linden  c/o   vdlinden@fwi.uva.nl (Frank van der Linden)
*** fd.c.old	Fri Nov 19 20:17:14 1993
--- fd.c	Fri Nov 19 21:03:41 1993
***************
*** 84,88 ****
  	{ 9,2,0xFF,0x23,40,720,2,1,2 },	/* 360k floppy in 1.2meg drive */
  	{ 9,2,0xFF,0x2A,40,720,1,1,2 },	/* 360k floppy in DD drive     */
! 	{ 9,2,0xFF,0x2A,80,1440,1,0 },	/* 720K drive. PROBABLY WRONG	*/
  };
  
--- 84,88 ----
  	{ 9,2,0xFF,0x23,40,720,2,1,2 },	/* 360k floppy in 1.2meg drive */
  	{ 9,2,0xFF,0x2A,40,720,1,1,2 },	/* 360k floppy in DD drive     */
! 	{ 9,2,0xFF,0x2A,80,1440,1,2,2 },/* 720K drive. PROBABLY WRONG	*/
  };
  
***************
*** 339,343 ****
  	fdc = fd->fdc;
  	fdcu = fdc->fdcu;
!  	/*type = FDTYPE(minor(bp->b_dev));*/
  
  	if ((fdu >= NFD) || (bp->b_blkno < 0)) {
--- 339,343 ----
  	fdc = fd->fdc;
  	fdcu = fdc->fdcu;
!  	fd->ft = &fd_types[FDTYPE(minor(bp->b_dev))];
  
  	if ((fdu >= NFD) || (bp->b_blkno < 0)) {
***************
*** 486,495 ****
  {
   	fdu_t fdu = FDUNIT(minor(dev));
!  	/*int type = FDTYPE(minor(dev));*/
  	int s;
  
  	/* check bounds */
  	if (fdu >= NFD) return(ENXIO);
! 	/*if (type >= sizeof(fd_types)/sizeof(fd_types[0]) ) return(ENXIO);*/
  	fd_data[fdu].flags |= FD_OPEN;
  
--- 486,495 ----
  {
   	fdu_t fdu = FDUNIT(minor(dev));
!  	int type = FDTYPE(minor(dev));
  	int s;
  
  	/* check bounds */
  	if (fdu >= NFD) return(ENXIO);
! 	if (type >= sizeof(fd_types)/sizeof(fd_types[0]) ) return(ENXIO);
  	fd_data[fdu].flags |= FD_OPEN;
  

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