IDA: Auto-Commenting

Auto-Commenting is a nifty feature that you expect from any debugger. IDA is very capable at auto-commenting. Here is a classical example (please note that the example below comes from an obsolete version of IDA and that support has been much improved since.)

seg000:09D2 loc_0_9D2:                              ; CODE XREF: start+8CCj
seg000:09D2                 mov     al, 0
seg000:09D4                 mov     dx, 194Fh
seg000:09D7                 xor     cx, cx
seg000:09D9                 mov     bh, 7
seg000:09DB                 mov     ah, 6
seg000:09DD                 int     10h             ; - VIDEO - SCROLL PAGE UP
seg000:09DD                                         ; AL = number of lines to scroll window (0 = blank whole window)
seg000:09DD                                         ; BH = attributes to be used on blanked lines
seg000:09DD                                         ; CH,CL = row,column of upper left corner of window to scroll
seg000:09DD                                         ; DH,DL = row,column of lower right corner of window
seg000:09DF                 xor     dx, dx
seg000:09E1                 mov     word_0_15F, dx
seg000:09E5                 mov     ah, 2
seg000:09E7                 xor     bh, bh
seg000:09E9                 int     10h             ; - VIDEO - SET CURSOR POSITION
seg000:09E9                                         ; DH,DL = row, column (0,0 = upper left)
seg000:09E9                                         ; BH = page number
seg000:09EB                 mov     di, 546h
seg000:09EE                 call    off_0_16C
seg000:09F2                 mov     di, 4B4h
seg000:09F5                 call    off_0_16C
seg000:09F9                 mov     di, 54Ah
seg000:09FC                 call    off_0_16C
seg000:0A00                 call    off_0_16E
seg000:0A04                 mov     ax, 4C00h
seg000:0A07                 int     21h             ; DOS - 2+ - QUIT WITH EXIT CODE (EXIT)
seg000:0A07                                         ; AL = exit code