BUGS.TXT

There are currently no serious bugs known to be in Enhanced DR-DOS, but you
might encounter problems with software that is not adapted to some of its
features. In particular, you should read the following warnings before using
any disk tools:

Warning: Beginning with version 7.01.04, DR-DOS is able to use the LBA BIOS
functions to access hard disk partitions outside the 7.8 GB limit defined by
the old CHS (cylinder, head & sector) system. This is no problem for any disk
tools that use DOS functions to access these partitions, however, there are
many old tools that are not LBA-compliant which use low-level BIOS calls to
access hard disks. When used on partitions that are not within the space
accessible via CHS these tools could possibly write data to the wrong sectors
on the hard disk and thus cause severe damage. This is not a bug in DR-DOS, but
a limitation of these tools. Some of the disk tools that are included in the
distributions of DR-DOS 7.0x like fdisk, format, diskopt, etc. may also fall
into this category. Until they have been tested on LBA partitions and it has
been found that they are safe to use, do not use them without making a backup
of your hard disk first.

Warning: Beginning with version 7.01.05, DR-DOS supports FAT16 partitions with
a cluster size of 64 KB. This feature has been tested and found to be working.
However, until someone has done extensive tests and it has been found that it
is generally safe to use, use precautions before using it on partitions that
contain valuable data. Also, please note that many disk tools do not expect to
see this feature on a DOS based machine, so they most likely do not support it.
Windows NT and FreeDOS support it, so tools written for these operating systems
should be safe to use.

Update: Chkdsk seems to work with both LBA partitions and 64K clusters.

Warning: In version 7.01.06 I have introduced support for the FAT32 file system
to DR-DOS. However, many disk tools (including those of DR-DOS 7.0x) do not
support FAT32, at least not in DOS. You should not use any disk tools on FAT32
drives unless you know that they are compatible with FAT32 and large drives.
Tools written for FreeDOS or MS-DOS 7 and higher should be safe to use.

Enhanced DR-DOS v7.01.07 again adds new features that might prove incompatible
with older software:
- It now supports drives with 128K cluster size. This is mostly untested, since
  there are no DOS tools that support this cluster size. Existing tools
  probably cannot handle this size. Due to limitations of the bootsector and
  BDOS loader code, it also cannot boot from those drives.
  Update (30.5.2005): The new DR-DOS FORMAT v1.0 supports this cluster size.
- Several config.sys commands that DR-DOS 7.03 uses to move data structures to
  upper memory are now supported, some of which have been enhanced to provide
  additional benefits. Older software might expect to see these structures in
  lower mem, so you might have to turn those options off to run it.
  Also, because of enhancements of the internal memory handling, some older TSR
  programs might not work properly if you load them with INSTALL/HIINSTALL in
  config.sys. If that is the case, use INSTALLLAST/HIINSTALLLAST instead.

Starting with version 7.01.08 WIP (15.1.2006), Enhanced DR-DOS supports the
FAT+ filesystem extension which allows files to become as large as 256 GB - 1B,
space on the drive permitting. This support is automatic and does not require
any changes to existing drives. FAT+ is fully downward compatible with FAT for
drives which only contain files that are below the 4 GB limit of the older FAT
filesystem in size. To prevent non-FAT+-aware OSes from accidentally accessing
FAT32+ drives which contain larger files, it is recommended to set the FAT32
version number in the boot block of these drives to 0.1 (major version 0, minor
version 1) to indicate that they should not mount these drives.

Other things known not to work perfectly:
- The DIR command currently does not show the actual size of files larger than
  4 GB; this will probably be fixed in one of the next WIP versions.
  Update (12.4.2008): DIR at least now shows large file sizes if DOSLFN is
  loaded.
  Update (28.3.2009): DIR no longer needs DOSLFN to show large file sizes.
- Function Int 21h/AX=71A6 is supposed to give the "Unique File Identifier" of
  an open file. Until someone can tell me how Windows determines this value, it
  will be shown as 0 instead. Also, the number of "links to this file" is
  always assumed to be 1.
- Function Int 21h/AX=71A7,BL=01 treats all time stamps as local, simply
  because there is no time zone information in DOS. This also affects the time
  stamps given by function 71A6. The inverse function BL=00 has not been
  implemented, yet.
- DOSLFN and probably also other LFN tools use some reserved bytes in directory
  entries to store additional time stamps; alas, some of those bytes are used
  by DR-DOS as part of the file password protection system. The result is that
  hidden files with a creation file time set may show up in directory searches
  not looking for hidden files. If this is a problem to you, you can either
  compile a version of DRDOS.SYS without specifying /DPASSWORD in MAKE.BAT or
  not use hidden files with Long Filenames.
  Update (6.1.2009): I have solved the problem by making Enhanced DR-DOS ignore
  all file passwords on FAT32 drives (on which passwords cannot be used,
  anyway) and for files with no access rights set (which cannot happen for
  actually password-protected files). However, using DOSLFN on password-
  protected files will probably corrupt the passwords or accidentally unprotect
  the files.
- Enhanced DR-DOS 7.01.08 WIP (28.3.2009) includes partial support for several
  LFN functions (7143h,714E/4Fh,71A1h) which are used by COMMAND.COM or other
  tools, however, they do not actually support LFN functionality. If you need
  full LFN support, you have to load DOSLFN or a similar TSR. Also, the
  functions 714E/4Fh do not support two or more concurrent searches.