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#42 Support 3rd/4th floppy drive on PC-XT

Kernel (17)
Eric Auer

Moved from our bugzilla item 1176:

*C Moritz* 2002-06-12

i have a 486 system with 3 floppys: a:1.44, b:1.2,1 f:360K and a 4th that is
not installed and comes
up at boot as none. The 820 Mb HD is C:, D:, and E:, also an LS120 that is H:
and a ram disk as I:
with 16Mb. This works fine wit MSD 6.22 but with Freedos, the 360 K is not
recognized and because
so far I haven't been able to make HIMEM load don't have a ram disk on Freedos
either. he floppys are
or have a 4-floppy legacy controller (8-bit) with its own ROM. I do this
because I have 30 years of data on 360K and 1.2Mb
disks ans also, because I've found over the years that 360K disks can be
depended upon to hold their
databetter than any of the others. Would ike suggestions about how to get the
kernel to be aware
that there can be more than 2 floppys. The LS120 is on one of the IDE ports
and works fine. It would
be nice if it could come up as the A: drive, since it can also read 1.44 Mb
I have to do this in a library and don't have any e-mail facilities. Hope
somehow I will find any answers
here somewhere, but must say you make it hard to even find this spot to put
this out
C Moritz, 32 Wetherbee St Acton MA o1720

*Bernd Blaauw* 2002-06-13

How does the separate floppycontroller work in normal DOS? You say
option rom, but do you need a device driver for dos?, or config.sys's
DRIVPARM command (not implemented in freedos yet)?
there's 2 options: use fdxms.sys or himem.exe provided with freedos
my system's config.sys: device=c:\dos\bin\fdxms.sys
LS120 as A: -> bios issue I think.
Else you have no option but to keep working with your current OS,
though it would be a big leap for FreeDOS to have your configuration

*Eric* 2004-01-28

As far as I know, only the PC-PC and PC-XT had floppy
controllers which could actually be used for more than
2 floppy disk drives. All later PCs would only allow
a third or fourth floppy drive if you connect a second
controller, which would not normally be supported by the
BIOS. Without BIOS support, you would need extra drivers.
I think this problem can therefore be treated as very
low priority. Changing to "enhancement".

*Eric* 2004-06-12

To support a 3rd floppy drive, you need an
extra drive letter. Which ones should be used?

a) if secondary floppy controller (up to 4 drives
possible?) is found, use a: ... d: for floppy.
some older DOS versions did that.

b) allocate drive letters after harddisk drive
letters but before ramdisk / cdrom drive letters
(XT can only have EMS or DOS-RAM ramdisks and
as far as I know only 286+ support cdrom...)

c) use a driver.sys tool which allocates a drive
letter and sets configuration. Might be useful
if BIOS does not report correct drive properties.
driver.sys could be replaced by a builtin kernel
config.sys option like driveparm (which changes
DOSes idea of drive properties for existing floppy
drive letters but does not normally allow you to
allocate new drive letterS)...

(MSDOS 6 seems to do b for controllers with own ROM)


  • Eric Auer

    Eric Auer - 2008-03-09
    • priority: 5 --> 2
  • Kenneth Davis

    Kenneth Davis - 2010-08-15
    • labels: --> Kernel
    • assigned_to: nobody --> perditionc
  • Nobody/Anonymous

    Sourceforge.. Retweeted it :)