1). About HDEDIT

 HDEDIT is a disk editor. It accesses disks on a low level. It works
 on DOS, Windows 9x and Windows XP (user needs administrator rights).
 It's intended for experienced users only. Since there are no
 warnings when the disk is written to, the user must know what he/she
 is doing.

 HDEDIT.EXE is the DOS/Windows 9x version, HDEDITW.EXE is the Windows
 XP version.


 2). How to use HDEDIT

 HDEDIT accepts a drive number as command line parameter. This
 has to be the drive number used by Int13, so the first HD is
 0x80, the next will be 0x81 and so on. If this parameter is not 
 given, HDEDIT will start with the first HD.

 HDEDIT has two modes, View mode and Edit mode. In the beginning the
 program is in View mode and sector 0 is shown. With keys 
 "Cursor left"/F5 or "Cursor right"/F6 the current sector will be
 changed. To select a sector directly use the TAB key. To change
 the content of a sector, switch to Edit mode with F8. F7 will
 switch back to View mode.
 In Edit mode the TAB key can be used to switch between columns
 "Hex" (left) and "Text" (right). The changes are made in memory
 only (working area). To make them permanent menu item "Rewrite
 sector" has to be selected. But HDEDIT will also ask to rewrite
 data if the user is about to change sector or terminate the program.

 With menu items "Load from..." and "Save as..." sectors can be 
 loaded from/saved to a file. Be careful if more than one sector is
 loaded from a file - just the last one is kept in the working area,
 the rest is written to the disk immediately!


 3). Installation

 HDEDIT consists of 3 files:

 - HDEDIT.EXE      binary for DOS and Windows 9x
 - HDEDITW.EXE     binary for Windows XP
 - HDEDIT.TXT      this file 

 Just copy these files in a directory and run HDEDIT(W).EXE. To 
 uninstall delete these files.


 4). Troubleshooting/Hints

 - To access disks > 8 GB (exactly 8032 MB), HDEDIT will use Int 0x13
   BIOS extensions. Only if these extensions aren't implemented the 
   (old) functions for read and write will be used. If the extensions
   don't work properly (in some very old BIOSes), HDEDIT won't work 
   either.

 - HDEDIT is a DPMI application, but it is not compatible with DPMI 
   hosts like CWSDPMI, which don't provide DOS API translation.
   Therefore, if HDEDIT is to run in pure DOS, in must be ensured
   that CWSDPMI is not loaded residently. Then HDEDIT will use its
   internal DPMI host.

 - Changing the text screen resolution might not work reliable in
   fullscreen mode under Windows.


 5.) History

 22.09.1999, v1.00:
   - initial
 03.12.1999, v1.01:
   - bugfix: save to file had a problem
 28.04.2000, v1.02:
   - HDPMI32 was DEBUG version
 20.06.2001, v1.03:
   - integrated Win32 version (Win9x only)
 31.05.2002, v1.04
 21.06.2002, v1.05
 11.09.2004, v1.06
 25.10.2006, v1.07:
   - load+save with variable number of sectors.
   - Win9x and German versions deleted.
 28.07.2007, v1.08:
   - bugfix: failed if first HD had a sector size of 0x200, but other
     drives had a bigger one.
   - Both '/' and '-' accepted as option prefix.
   - HDPMI32 deleted.
 08.08.2007, v1.09:
   - support for floppy disks added.
   - bugfix: 34 lines video mode didn't work always.
   - bugfix: pressing Ctrl-Break caused a GPF.
 01.09.2007, v1.10:
   - hdedit.exe linked as stand-alone binary, includes HDPMI32.
 14.01.2008, v1.11:
   - hdeditw.exe added.
 02.03.2008, v1.12:
   - format of hdedit.exe changed to zero-based flat.
 03.07.2008, v1.13:
   - bugfix: due to a memory leak HDEDIT (DOS) displayed a "read
     error" after some sectors (~135-140) have been read.
 16.07.2008, v1.14:
   - source code added.
   - bugfix: the "hex editor" module linked into the binaries was
     outdated and might have caused a GPF.
   - bugfix: there was a breakpoint byte 0xCC left in the source
     which was executed when a read error occured.
   - bugfix: the dialog which asked the user if a modified sector
     is to be rewritten to the disk wasn't displayed in v1.12-1.13.
   - bugfix: CHS read/write didn't work in DOS versions v1.12-1.13.
   - bugfix: FD access didn't work in versions v1.12-1.13.
 02.08.2009, v1.15:
   - source code added in v1.14 wasn't complete.
 09.02.2010, v1.16:
   - bugfix, HDEDIT.EXE: rewrite of sector sometimes was rejected 
     ('Error writing sector') because flags for int 13h, ah=43h were set
     incorrectly.


 6.) License

 HDEDIT is FreeWare.

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