Subject: The list of floppy devices and a suggestion...
To: None <>
From: Dave Burgess <>
List: current-users
Date: 07/09/1994 17:31:47
Once upon a time, someone asked if the list of the new floppy devices
was documented anywhere but the soure code in fd.c.  The answer was NO
until just a minute ago.  I added the list for these devices to the FAQ
(in section 6) so that anyone that wanted to use mtools (until MSDOSFS
support is repaired) wouldn't have to wade through the source.

Here is the entry and the list:

6.5	How can I use mtools with the 'new' floppy naming convention?

	With the adoption of BSD 4.4, there is a new way of accessing
	the floppy disk drive types.  The method uses the minor device
	number to specify different media sizes and densities.  These
	densities are established by a table from the file 
	/usr/src/sys/arch/i386/isa/fd.c (in NetBSD, your mileage may
	vary).  The table in FreeBSD's fd.c is likely to be slightly

	The order of the entries defines the order of the minor
	numbers, so the table below has the following characteristics:

 	    /dev/fd0a	1	/* 1.44MB diskette */ 
	    /dev/fd0b	2	/* 1.2 MB AT-diskettes */ 
	    /dev/fd0c	3	/* 360kB in 1.2MB drive */ 
	    /dev/fd0d	4	/* 360kB PC diskettes */ 
	    /dev/fd0e	5	/* 3.5" 720kB diskette */ 
	    /dev/fd0f	6	/* 720kB in 1.2MB drive */ 
	    /dev/fd0g	7	/* 360kB in 720kB drive */

	struct fd_type fd_types[] = {
        	{ 18,2,0xff,0xcf,0x1b,0x6c,80,2880,1,FDC_500KBPS,2,"1.44MB"  },
        	{ 15,2,0xff,0xdf,0x1b,0x54,80,2400,1,FDC_500KBPS,2,"1.2MB"   },
        	{  9,2,0xff,0xdf,0x23,0x50,40, 720,2,FDC_300KBPS,2,"360KB/AT"},
        	{  9,2,0xff,0xdf,0x2a,0x50,40, 720,1,FDC_250KBPS,2,"360KB/PC"},
        	{  9,2,0xff,0xdf,0x2a,0x50,80,1440,1,FDC_250KBPS,2,"720KB"   },
        	{  9,2,0xff,0xdf,0x23,0x50,80,1440,1,FDC_300KBPS,2,"720KB/x" },
        	{  9,2,0xff,0xdf,0x2a,0x50,40, 720,2,FDC_250KBPS,2,"360KB/x" },

	In order to add a new device (such as a 2.44 Meg floppy) new
	tables entries are theoretically all that would be needed.  As
	new entries are created, the minor device numbers would
	increase and the associated device names would be added.


Now that we have adopted this method, would it be appropriate to add a
more logical naming convention to our device directory.  Something
along the lines of Sun or SCO naming would be kind of nice, and would
take the voodoo out of figuring out the method....

Just a thought.