DEBUG

Starts the Debug program, which you can use to test and debug executable    
files.

For information on DEBUG command-line syntax, type DEBUG /? at the command
prompt.

For a list of Debug commands, start Debug, and then type ?.

For more information about Debug commands, see the MS-DOS Technical
Reference, which comes with the MS-DOS Resource Kit. To order the
Resource Kit, use the coupon in the back of your MS-DOS User's Guide.