CD! 1.3 - an improved Change Directory command that sets the errorlevel.
The CD command that comes with MS or PC DOS has three flaws:
1.  It does not set the ERRORLEVEL for Invalid directories.
2.  It fails when there is a trailing backslash on the name.
3.  You cannot hide its error messages with >NUL: redirection.
CD! acts just like CD except that it fixes these three problems.
CD! is slower since it is must be loaded each time, whereas CD
is internal to DOS's COMMAND.COM.
MASM/OPTAsm source included. May be freely distributed
and used for any purpose except military.
Warning CD! only works with 8.3 filenames.
Version 1.3 just embeds the new address and phone number.