v2.50

• DebugR fix: debugger assumed a 32-bit ring0 SS register on init;
  if this wasn't true, a crash may have occured.
• fix r cmd: the disassembler tried to show memory contents for the LEA
  instruction - this may have caused a GPF.
• DebugX fix e cmd, prompt mode: segment part changed to scratch sel
  after first line in protected-mode if it was a r/o selector.
• fix e cmd, prompt mode: '-' after byte input did skip that input.
• fix u cmd: address size prefix 67h for string instructions.
• fix n cmd: names > 128 chars may have modified debug's code seg.
• fix l & q cmd: failure of debuggee termination was ignored and the
  command continued, leaving an orphaned debuggee in memory.
• fix a cmd: regression since v1.18: "call/jmp [mem_ref]" without a size
  given did default to a far call/jmp.
• fix u cmd: operand size prefix 66h for 8/16/32-bit relative jmps.
• fix a cmd: NEar qualifier was accepted/ignored for immediate far
  jmp/call.
• u cmd, call far [mem]: qualifiers "FAR"/"DWORD FAR" changed to
  "FAR16"/"FAR32".
• DebugR(L): Q cmd may be activated for this variant.
• cmds bp/bc accept up to 4 permanent breakpoints.
• cmds bp/bc implemented, but inactive for Debug & DebugX; activated in
  DebugXg & DebugXv variants.
• G/T/P cmds: if possible, 386 debug registers will be used to set
  temporary breakpoints. Active for DebugX, DebugR(L).
• new cmdline options /s and /v for debugger variants that may use
  hardware breakpoints ( option /v not for DebugR(L) variant ).
• g cmd: if a breakpoint cannot be written, the cmd is aborted.
• Debug & DebugX may now be created in .exe file format.
• mktables.c: creates ASMTBL.INC/DISTBL.INC instead of DEBUGTBL.INC.
• cmds a, u: instruction RDTSC added.
• another variant of DebugR - DebugRV, with support for V86 mode.
• DebugR(V) dt cmd: optionally displays trapped ports.
• DebugRV di cmd: displays IDT & IVT vectors.
• DebugR rn cmd: won't run cmd if CR0.EM is set.

v2.02

• fixed S cmd: position display was corrupted in v2.00-v2.01.

v2.01

• fixed: addr/opsize prefixes "toggle", but just once.
• fixed: debug exceptions occuring inside debug are now ignored.
• fixed dm cmd: invalid last mcb no longer displayed.
• added a ring0 (PL0) variant for long mode - DebugRL.bin.
• DEBUGR(L): added bp & bc cmds.

v2.0

• fixed: routine int21ah9 did use DOS, even if InDos flag was set.
• fixed: reading stdin from file wasn't fully MS Debug compatible.
• fixed: correctly handle tabs if output is via BIOS.
• fixed L/W cmds: error msg for read/write drive was crumbled since v1.18.
• ensured the correct video page is used when debugger has to display something if the InDOS flag is set AND page swapping is active.
• mktables.c fix: didn't generate a valid debugtbl.inc.
• added a "boot" variant of the debugger - DebugB.bin.
• added a ring0 (PL0) variant of the debugger - DebugR.bin.
• DI cmd may be activated for standard DEBUG.COM.
• DEBUGX fix: restore hooked protected-mode interrupts when client terminates.
• DEBUGX fix: c & s cmds finally work with 32-bit offsets.
• DEBUGX fix, e cmd: generate a GPF if no data alias can be found for a code segment ( instead of silently skip the write ).
• DEBUGX fix: disassembly of [CS:IP] in register dump may have caused a GPF in debugger if the memory address was beyond seg limit - 3.
• DEBUGX fix, g cmd: if multiple breakpoints with different segment parts were set in protected-mode, hazardous writes may have happened.
• DEBUGX fix, m cmd: '$' qualifier for the source address segment was rejected.
• DEBUGX fix, c & m cmds: if both source and destination segment parts were readonly, the scratch selector was used twice.
• DEBUGX: added cmdline option /2.
• DEBUGX: hook into protected-mode debug interface Int 41h and make debugger visible there.
• DEBUGX, a & e cmd: usage of scratch descriptor for readonly segments now hidden, so the displayed address' segment part isn't changed.
• DEBUGX, a & d cmd: default segments are no longer automatically converted to selectors during initial switch to protected-mode.
• DEBUGX: exceptions 0dh/0eh are set/reset on debugger entry/exit.
• DEBUGXV: stop in debugger if SYSREQ is pressed.

v1.29

• DEBUGX bugfix c/d/e/m/s-cmd: an offset beyond 0ffffh was rejected if the segment descriptor's 'default-size' flag wasn't set.
• DEBUGX bugfix e-cmd interactive mode: offset increment and decrement was always 16-bit only.
• DEBUGX bugfix e-cmd non-interactive mode: skip test for 16-bit wrap if segment is larger than 64 kB.
• regression in debugxg. v1.28: the driver version crashed when it became active because the new mode detection code always returned status "in protected-mode".
• regression in DEBUGX, v1.28: on rare conditions, the debugger used a wrong pointer (debuggee's SS:ESP instead of SS:SP) to clear TF on the debuggee's stack.
• clear TF if child process is to be canceled ( else a "memory corrupt" error may appear in DOS ).
• DEBUGX, e-cmd: don't use int 21h, ah=8 directly in interactive mode.
• volume unlock: removed setting registers dx/bh, since useless.
• DEBUGX: behavior of q-cmd changed if debuggee is in protected-mode.Entering 'q' at the '#' prompt will (hopefully) make the debuggee
  exit protected-mode and debugx's real-mode prompt '-' should appear.
• DEBUGX: new command variant 'qq' to terminate a DPMI client that has intercepted protected-mode int 21h and refuses to quit.
• another variant - DEBUGXV - may be created. It allows to flip video screen between debugger and debuggee.

v1.28

   - DEBUGX bugfix e-cmd: used wrong offset when reading from 32-bit 
     segments.
   - DEBUGX bugfix d-cmd: hiword(ecx) wasn't cleared, resulting in a
     "default" length for 32-bit segment dump > 128.
   - DEBUGX bugfix g/t/p-cmd: if debuggee is stopped in protected-mode,
     saved stack at debugger's PSP:[2Eh] must not be "adjusted".
   - added debug displays (created if _DEBUG is defined)
   - DEBUGX: int 2Fh, ax=1686h to detect mode no longer used - this makes 
     interrupt 2Fh traceable.
   - 'e' cmd: don't stop input after byte '0d' has been entered

.

v1.27

   - added new variant DEBUGXU.COM. This version does not use int 15h, 
     ah=87h inside the DX command, thus avoiding to disable a possibly
     active unreal mode. The catch is that this version's DX command won't
     work in V86 mode.
   - disassembler handles operand size prefix for one-byte "push <imm>" 
     opcodes correctly. OTOH, for 2/4 byte "push <imm>" opcodes, the 
     disassembler no longer displays the operand size, since the size
     is obvious.
   - if InDOS flag is set, a '!' is preceding the debugger prompt.
   - BIOS used when waiting for a key in help msg display.
   - 'e' cmd uses BIOS if InDOS flag set.