It is a full-screen debugger displaying both Turbo Pascal or Turbo C source and corresponding assembly-language instructions, with powerful capabilities for setting breakpoints, watching the execution of instructions, monitoring machine registers, etc.
The TDH386.SYS driver also adds breakpoints supported in hardware by the 386 and later processors to all three debugger programs.
TD386 allows some extra breakpoints that the other debuggers of the era do not (I/O access breaks, ranges greater than 16 bytes, and so on).
[5] In a February 1989 overview of optimizing C compilers, the magazine described it as "the best source debugger".
Hardware breakpoints supported by the 386 and later processors are available if TDH386.SYS is loaded by including "DEVICE=