1. About Deb16f

 Deb16f is a debugger for DOS real-mode and 16-bit DPMI applications. Its
 advantages/disadvantages are:

 + may trace mode switches
 + should be able to debug applications with mixed (16/32-bit)
   code segments
 + dissassembler knows full pentium instruction set
   including MMX and ISSE.
 + although looking a bit like "debug.exe" it is no problem
   for the debugger to trace through the DOS kernel code
 + a second video adapter is supported. As well, the debugger
   may be controled by COM port communication.
 + graphics applications may be debugged locally
 + automatically uses debug registers if it cannot write
   a breakpoint, so stepping through ROM is no problem.
 - has a simple line-oriented user interface.
 - is unable to debug at source code level


 2. How to start the Debugger

 Just enter "deb16f" on the command line.


 3. How to use Deb16f

 Deb16f has an integrated help function which describes most
 of its features. To start with it type

 - "?" for a list of available commands.
 - "? ?" to display help index. Each topic displayed here may
   be displayed in detail by entering "? <topic>"
 - "? keys" displays some help about keyboard usage inside Deb16f
 - "? cmdline" displays format of command line accepted by Deb16f

 A debuggee is loaded by "Load" command. Type "? L" to display
 format of this command. After a debuggee is loaded you may single-
 step through it by pressing F8 or just enter "G breakpoint"
 to execute debuggee in real-time until breakpoint is reached.

 Under some circumstances it may be necessary to disable the
 NE file loader from inside the debugger before loading a
 debuggee. This is the case if the debuggee is in NE format,
 but requires its own loader/stub to be executed. Use command
 ".LDR 0" to disable the loader. The debuggee will then be executed
 as a new DPMI client.

 Please note that this version can only debug 16-bit DPMI clients.
 All commands related to PE files are unknown by Deb16f.
 For 32-bit clients there exists another version called Deb32f.


 4. How to debug Apps using Graphics
 
 To debug apps which use graphics (like windows 3.x for example)
 it would be best to use a secondary display adapter of course. 
 If this isn't available screen swapping must be turned on by setting 
 debugger variable SCREENSwap=1. To force the debugger in single-step
 mode to switch screens in any case set bit 4 (=10h) of variable TRACEFlags.

  There a 2 dlls provided for graphics screen switching, DEBFVESA.DLL
 - which is loaded as default - and DEBFVGA.DLL. DEBFVESA may be modified,
 since source code is included. DEBFVGA doesn't require VESA and should
 work with any VGA adapter. It may be used instead of DEBFVESA if the
 latter fails to work. To tell the debugger to load DEBFVGA add a line
 in debxxf.ini:
 
 GraphHlp=DEBFVGA.DLL


 5. Files Overview

 - deb16f.exe:   a simple executable to load the debugger core
 - deb16f.ovl:   the debugger itself
 - rmdbghlp.bin: helper code which will be loaded into
                 conventional dos memory to provide support for
                 real/v86 mode debugging.
 - debxxvdd.dll: a VDD to support the debugger when running in NTVDM.
 - debxxf.hlp:   a text file which will be loaded by the debugger
                 at startup. contains help topics and error messages.
 - debxxf.mac:   contains macros for the debugger
 - debxxf.ini:   profile file for the debugger
 - dpmild16.exe: HX's NE file loader, required to load deb16f.exe.
 - showfile.dll: a 16-bit NE dll which is a fullscreen hex editor
                 and used by the debugger for its "type" command
 - symbhdld.dll: a 16-bit NE dll to find names of exports
 - debfvesa.dll: a 32-bit NE dll to save/restore screen if debuggee is
                 in graphics mode. Knows VESA and is loaded as default.
 - debfvga.dll:  another dll to save/restore screen if debuggee is in
                 graphics mode. Knows/uses VGA only.
 - debfvesa.zip: source code + makefile to create debfvesa.dll.
 - deb16f.txt    the file you are reading just now.


 6. Copyright

 Deb16f is freeware. Copyright 1993-2008 Japheth.

 Japheth