screwy format message

[Wolf Paul]

In article <1029 at hawkmoon.MN.ORG> det at hawkmoon.MN.ORG (Derek E. Terveer) writes:
>> There is a coding scheme
>> built into the minor device number of the file (device node) that was opened
>> and in it contains info such as hi/low density, etc. My guess is that you've
>> got some way bogus minor device number for f13ht or a corrupted binary.
>Ok -- that begs the question: "what are the correct minor device numbers for
>3.5" floppies?"  This is what i currently have:
> ...
>Also, what do each of the bits in the minor device numbers mean?  There doesn't
>seem to be any documentation for these things.  I have sort of made some
>guesses but, these guesses are probably wrong.

See below. This table was originally posted by Mark Zenier about a year ago,
and I confirmed/modified it in conversation with John Plocher who was then
Microport's Customer Service Manager.

>When i *do* format a 3.5" disk,
>it reports that 80 (0..79) tracks have been formatted; the same as for 5.25"
>disks, so it must not have the correct minor device number.

That does not follow; both 720K and 1.44M 3.5" disks ARE INDEED formatted as
80 tracks -- 720K disks with 9 sectors/track, 1.44M disks with 18 sectors/track.
The message from format would properly be the same.

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 (double-step)
    +---------------- 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)
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)

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 * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101
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        NOTICE: As of July 3, 1989, "killer" has become "attctc".