The following are some other debuggers which you might want:

gdbXXXbn.zip -- gdb, the GNU Debugger

gdbXXXdc.zip -- docs for the above

fsdbXXX.zip -- an alternative, full-screen debugger like Borland's td (but NOT a source-level one), supports DPMI, doesn't support 80x87

ldbgXXX.zip -- yet another debugger, similar to fsdb, supports 80x87, but doesn't support DPMI.