cmp
Below is a summary of the options that Diff'nPatch accepts for byte by byte comparison. Note that the output of this command is limited to 12000 bytes: this is a limitation on the number of bytes output by the comparison command, not on the number of bytes compared. The maximum number of bytes to compare can be set with the max num of bytes option.
-b
--print-bytes
^
followed by a letter of the alphabet and precede bytes
that have the high bit set with M-
(which stands for "meta").
-i skip
--ignore-initial=skip
-n count
--bytes=count