Linux device drivers...followup...

[gaf at blu.org (Jerry Feldman)]

fd0D360 == Double Density 360K (single sided)
fd0D720 == Double Density 720K (double sided).
The names themselves only have meaning to humans. SuSE is a bit different:
brw-rw-rw-   1 root     disk       2,  40 Dec  3 09:39 /dev/fd0h1440
brw-rw-rw-   1 root     disk       2,  28 Dec  3 09:39 /dev/fd0u1440  
brw-rw-rw-   1 root     disk       2,  41 Dec  3 09:39 /dev/fd1h1440
brw-rw-rw-   1 root     disk       2,  29 Dec  3 09:39 /dev/fd1u1440 
Note that the minor numbers are different. The device driver uses the minor 
numbers.
There is a man page for fd. I have taken some excerpts from it. Basically, 
a device driver uses the minor number to convey certain information, such 
as the drive number, capacity, etc. Each driver may use a different method.

Drive independent device files which automatically  detect  the media 
format and capacity:

       Name   Base minor #
       --------------------
       fdn    0

       5.25 inch double density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnd360      360K     40     9       2       4                       


      3.5 inch high density device files:

       Name         Capac.   Cyl.   Sect.   Heads   Base minor #
       ----------------------------------------------------------
       fdnH1440     1440K    80     18      2       28

"Kevin M. Gleason" wrote:
> Hi all,
> After Jerry's response I did a lookup of floppy drives in /dev directory and
> obtained a list of those beginning with fd0 (and identical list was there for
> fd1):
> fd0
> fd0D360
> fd0D720
> fd0H1440
> fd0H360
> fd0H720
> fd0d360
> fd0h1200
> fd0h360
> fd0h720
> Can I assume that when the system starts up it looks in ROM Bios and matches 
> up
> my 1.44M floppy drive with its device driver fd0H1440 and uses its device inf
> o?
> What do all of the other numbers stand for and why are there repeats (360
> appears four times)? If these numbers reference disk capacity does the letter
> preceeding it represent drive size (8", 5 1/4", 3 1/2")?
> Thanks.
> 
> Kevin
> ---------------------------------------
> Jerry Feldman wrote:
> 
> > First, the files in the /dev/ directory are usually device special files an
> d
> > rarely are there normal files. When you do an ls -l, the first character
> > before the permissions says whether it is a character or block device.
> > In the following, ptyp0 is a character device with a major number of 7,
> > and a minor number of 0.
> > crw-rw-rw-   1 root     system     7,      0 Oct 22 14:48 ptyp0
> > Each driver is identified by a major number, and the device is generally
> > the minor number, but that actually depends on the driver. Floppy names
> > are normally set up as something like /dev/fd01440. There is a whole
> > bunch of them. I don't have a linux system that I can log into from here.
> >
> > On 21 Feb 00, at 10:22, Kevin M. Gleason wrote:
> >
> > > I was playing around on my Linux box and had some questions about files
> > > in /dev.
> > > If fd0 is used to define the first 3 1/2" high density floppy what other
> > > device drivers might I expect to see for the same size drive?
> > >
> > > Or other drivers on my computer (I have used the cdrom is09660).
> > >
> > > Are there drivers for the old 5 1/4" floppy disk drives?
> > >
> > > Thanks for your help.
> > >
> > > Kevin
> > >
> > > -
> > > Subcription/unsubscription/info requests: send e-mail with
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> >
> > --
> > Jerry Feldman
> > Contractor, eInfrastructure Partner Engineering
> > 508-467-4315 http://www.testdrive.compaq.com/linux/
> >
> > Compaq Computer Corp.
> > 200 Forest Street MRO1-3/F1
> > Marlboro, Ma. 01752
> > -
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> 
> -
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> 

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix user group
http://www.blu.org


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