BPATCH.C
Original code written by Garry M. Johnson and Steven Lisk.

Neat code and program.  Dump or edit files (binary or acsii), displayed
by 256-byte records in side-by-side hex and ascii formats.  Various
other features (eg, toggled swap within byte pairs).

Jörg's remark:

The most interesting feature of this editor is that it doesn't load the
entire file at once, unlike all other hex editors.  Thus, you can browse
and edit very large files or even raw disks.