[plug] `dd` and SSDD floppies?

[John Summerfield]

> Hi folks,
> 
> I'm trying to read and write 386K 3.5" SSDD diskettes with dd. Main reason
> is to back store some CP/M disk images to harddrive (and maybe CDROM).
> 
> Various DOS applications can read and write to these disks, so the
> hardware's okay with the task. However, `dd` appears to fail when trying
> to read the non-existent second side of the disk.
> 
> I've tried the conv=noerror option, however, while it appears to gather
> data (with a whole lot of floppy thrashing), I have no confidence it could
> ever write this back to a floppy correctly.
> 
> Any help warmly accepted.

I think you're out of luck. /usr/src/linux/Documentation/devices.txt lists 
the devices supported by Linux. The floppies are:
    block       Floppy disks
                  0 = /dev/fd0          Controller 1, drive 1 autodetect
                  1 = /dev/fd1          Controller 1, drive 2 autodetect
                  2 = /dev/fd2          Controller 1, drive 3 autodetect
                  3 = /dev/fd3          Controller 1, drive 4 autodetect
                128 = /dev/fd4          Controller 2, drive 1 autodetect
                129 = /dev/fd5          Controller 2, drive 2 autodetect
                130 = /dev/fd6          Controller 2, drive 3 autodetect
                131 = /dev/fd7          Controller 2, drive 4 autodetect

                To specify format, add to the autodetect device number:
                  0 = /dev/fd?          Autodetect format
                  4 = /dev/fd?d360      5.25"  360K in a 360K  drive(1)
                 20 = /dev/fd?h360      5.25"  360K in a 1200K drive(1)
                 48 = /dev/fd?h410      5.25"  410K in a 1200K drive
                 64 = /dev/fd?h420      5.25"  420K in a 1200K drive
                 24 = /dev/fd?h720      5.25"  720K in a 1200K drive
                 80 = /dev/fd?h880      5.25"  880K in a 1200K drive(1)
                  8 = /dev/fd?h1200     5.25" 1200K in a 1200K drive(1)
                 40 = /dev/fd?h1440     5.25" 1440K in a 1200K drive(1)
                 56 = /dev/fd?h1476     5.25" 1476K in a 1200K drive
                 72 = /dev/fd?h1494     5.25" 1494K in a 1200K drive
                 92 = /dev/fd?h1600     5.25" 1600K in a 1200K drive(1)

                 12 = /dev/fd?u360      3.5"   360K Double Density(2)
                 16 = /dev/fd?u720      3.5"   720K Double Density(1)
                120 = /dev/fd?u800      3.5"   800K Double Density(2)
                 52 = /dev/fd?u820      3.5"   820K Double Density
                 68 = /dev/fd?u830      3.5"   830K Double Density
                 84 = /dev/fd?u1040     3.5"  1040K Double Density(1)
                 88 = /dev/fd?u1120     3.5"  1120K Double Density(1)
                 28 = /dev/fd?u1440     3.5"  1440K High Density(1)
                124 = /dev/fd?u1600     3.5"  1600K High Density(1)
                 44 = /dev/fd?u1680     3.5"  1680K High Density(3)
                 60 = /dev/fd?u1722     3.5"  1722K High Density
                 76 = /dev/fd?u1743     3.5"  1743K High Density
                 96 = /dev/fd?u1760     3.5"  1760K High Density
                116 = /dev/fd?u1840     3.5"  1840K High Density(3)
                100 = /dev/fd?u1920     3.5"  1920K High Density(1)
                 32 = /dev/fd?u2880     3.5"  2880K Extra Density(1)
                104 = /dev/fd?u3200     3.5"  3200K Extra Density
                108 = /dev/fd?u3520     3.5"  3520K Extra Density
                112 = /dev/fd?u3840     3.5"  3840K Extra Density(1)

                 36 = /dev/fd?CompaQ    Compaq 2880K drive; obsolete?

                (1) Autodetectable format
                (2) Autodetectable format in a Double Density (720K) drive 
only
                (3) Autodetectable format in a High Density (1440K) drive 
only

                NOTE: The letter in the device name (d, q, h or u)
                signifies the type of drive: 5.25" Double Density (d),
                5.25" Quad Density (q), 5.25" High Density (h) or 3.5"
                (any model, u).  The use of the capital letters D, H
                and E for the 3.5" models have been deprecated, since
                the drive type is insignificant for these devices.

I note that SS DOS formats are not supported. I expect that 360K formats 
will read IBM's 320K disk, but I haven't any to try (nor do I have a 5.25" 
drive).

-- 
Cheers
John Summerfield
http://os2.ami.com.au/os2/ for OS/2 support.
Configuration, networking, combined IBM ftpsites index.