One of my favourite DOS things was the DEBUG.EXE command. As far as I know, it was the only debugger that allows for the creation of debug files where you could do things like debug.exe < script.dbg to do low level things like replacing a disk partition table.
It was a very handy method of passing around binaries in text-oriented chat systems.
It was a very handy method of passing around binaries in text-oriented chat systems.