minor dev nums, bootable disks

[Wolf Paul]

In article <774 at n3dmc.UU.NET> brian at n3dmc.UU.NET (Brian Lloyd) writes:
 >
 >For uPort SysV/AT 2.4 (286).
 >
 >1.  What are the minor device numbers for floppy devices?  I need numbers
 >for 1.44Mb mini-floppy and 1.2Mb 5" floppy as the second floppy drives on
 >a generic AT clone.  I also need the minor dev number for 0s25 (that strange
 >bootable device) for a 1.44Mb mini floppy.

Please see the table enclosed at the end for a fairly complete list
of Microport 2.4 Floppy minor numbers.

 >2.  How do I create a bootable floppy disk for SysV/AT v2.4?
 >
 >I have the v2.4 distribution on 1.2Mb 5" floppies but I want to convert to
 >1.44 Mb mini floppies.

It is my understanding that you need to use "dd" to copy /etc/boot.fd
(or similar name, don't have a 286 UNIX handy) to the first block(s) of
the floppy, using the "complete disk" device.

Then you need to make a file system on the corresponding "all-but-first-track"
device (bit 7 set in the minor number), and create a minimal directory
hierarchy on it (/etc, /bin, /tmp, maybe more). Then you need to copy reqired
files, such as a kernel, /bin/sh, /etc/passwd, and any other commands you
need and can fit, to the appropriate directories on that floppy fs.

Here is the table for minor number coding:

    7 6 5 4 3 2 1 0
    | | | | | | | |
    | | | | | | | +-- if set, drive has 9 sectors/track
    | | | | | | +---- if set, drive is double-sided
    | | | | | +------ if set, drive has 80 cylinders
    | | | | +-------- Drive number ( 0 or 1 )
    | | | +---------- if NOT set, drive is high density (1.2 or 1.44)
    | | +------------ if set, drive is 3.5"
    | +-------------- if NOT set, read 40-cyl disk on 80-cyl drive (doublestep)
    +---------------- if set, skip cylinder #0 (INSTALL floppies, 0s25)

>From this then, result the following minor numbers:

For Drive 0:

Standard AT 1.2M :              01000110        70  (fd096ds15, 0s24)
Bootable AT 1.2M                11000110       198  (0s25)
Standard XT 360K :              00010111        23  (fd048ds9)
Old XT 320K :                   00010110        22  (fd048ds8)
Old XT 160 :                    00010100        20  (fd048ss8)
Quad Density 720K 5.25" :       01010111        87  (fd096ds9)
Double Density 720K 3.5" :      01110111       119  (fd0mf2dd)
High Density 1.4M 3.5" :        01100110       102  (fd0mf2hd)
Bootable HD 1.4M 3.5":          11100110       230  (??? Make up a name!)

And for Drive 1:  (Add 1000 binary, or 8 decimal to the numbers for Drive 0)

Standard AT 1.2M :              01001110        78  (fd096ds15, 0s24)
Standard XT 360K :              00011111        31  (fd048ds9)
Old XT 320K :                   00011110        30  (fd048ds8)
Old XT 160 :                    00011100        28  (fd048ss8)
Quad Density 720K 5.25" :       01011111        95  (fd096ds9)
Double Density 720K 3.5" :      01111111       127  (fd0mf2dd)
High Density 1.4M 3.5" :        01101110       110  (fd0mf2hd)

I have used these minor numbers successfully on my Uport 286 system until
I sold it late last year.
-- 
Wolf N. Paul
--------------------               ------------------
Until Sept 25, 1989:               As of Oct 2, 1989:
--------------------               ------------------
3387 Sam Rayburn Run               Kirschenallee 113
Carrollton, TX 75007               A-1220 Vienna, Austria
                                   (Europe)
wnp at attctc.dallas.tx.us            uunet!mcvax!iiasa2!wolfp