I remember exploring COMMAND.COM with DiskEdit. In going through the compiled code I realized that the common DOS commands, (DEL, COPY, etc.) basically had a 3

I remember exploring COMMAND.COM with DiskEdit. In going through the compiled code I realized that the common DOS commands, (DEL, COPY, etc.) basically had a 3 byte string after them in COMMAND.COM that would cause the program to jump to some subroutine that executed the actual operations underlying the command. If you, say, copied the jump code for DEL and pasted that where the REN(ame) command was, and then installed that new COMMAND.COM on the PC's in the schools lab, it caused some very frantic reactions ;)