Uncreative Labs

Posted: Sun Nov 01, 2009 5:41 am

Floppy Drives
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The BIOS has built-in support for low-density 5.25" and 3.5" drives only. I
didn't add support for high-density drives since I have a 4-drive floppy
controller with external BIOS that adds this support. Without an external
floppy BIOS, you can still use high-density drives but are limited to
low-density media.

There is another option for high-density drive support, which is to run
DR-DOS (6.x or 7.x, possibly earlier versions as well). DR-DOS has a unique
feature which actually loads software support for high-density drives at
bootup. As long as you have a high-density disk drive, you can boot DR-DOS
from a high-density disk no matter what the BIOS supports.

I found this in a bios file for the XT that i downloaded and am going to mod one of my XT's with. Maybe my Zenith that i just got once i clean it up. BUT Does DR-DOS 6.x or 7.x actually support that it says above? Can DR-DOS read High Density REGARDLESS of the controller? Does dr-dos use a trick kinda like the stunt Amiga pulled by slowing down the drive or somethin? Is this worth looking into?

Joined: 03 Feb 2006 Posts: 488 Location: pennsylvanai

due to sime kind of ":glitch"
or an assumption made by IBM, that the pc would use 80 tracg drives, the bios in the xt will see a 720k bootdisk. All you do is hook up the drive, either a 720 or a 1.44. It cannot tell the difference.,
BUT if you attempt to format the disk, it will format the disk as 360k.
If that version of DOS support the 720k disks, a device driver or driver.sys or drivparm will let the system ( using a standard XT floppy controller) use
the 720k disk.
IF you have a "special card" with a buios, ot a card like the compaticard that has NO BIOS but uses a device driver. You will be able to use a 360.720,1.2m, of 1.44 meg drive and disk.

The FIRST IBM PC is a special case.
if nit does NOT have the updated bios,
it doesn't even look for " bios extensions"
this means several devices cannot be used
Hi-Density floppy cards, ega and vga cards, hd controllers and scsi cards.
In other words anything that loads a bios in memory.

As far as using a 1.44 floppy drive in an xt. It can be easily done.
I am not entirely sure that a 1.44 floppy disk will be usable. I suspect if formatted as a 720k ( 80 tracks. 9 sectors) it can. The old 8088 cannot tell

Windows machines are a pain to do this with,. I have made 360k and 720k disks from a 1.44 floppy in a 1.44 drive. I may have had to change cmos settings and / or
used the "switches" in the command line.
Remamber old versions of dos did not accept or support anything other than 360k
dod 3.0 supported 1.2m ( with an AT controller on an AT)
BTW early AT/286's dis not support 720k disks according to an old artcile in PC World.

Joined: 19 Apr 2006 Posts: 261 Location: WisConSin

k2x4b524p wrote:

Floppy Drives
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Can DR-DOS read High Density REGARDLESS of the controller?

No,

but as they say only one way to find out I have never encountered a way of forcing a non-hd compatible controller to read HD media at full density.