uHex
A simple, fast and 8086-compatible hex editor
uHex is a simple and fast, multiplatform hex editor. It's primarily written for DOS, but compiles on POSIX just as well. uHex has been written with care to work fast even on an 8086 CPU, providing support for large files (up to 2 GiB) while using minimal amounts of memory. "uHex" stands for "micro Hex" (it should actually be spelled µHex, but DOS operating systems do not allow non-ASCII symbols in filenames, thus the official name became just "uHex").
uHex supports several video text modes...