If you want to detect if a string does not equal something you can use the less than and more than signs like:
if InputString$<>"Go" then gosub unknown1
One of the issues you'll see though is if you specifically look for "Go" then the user can type "GO" or "go" or "gO" and it still won't see it properly because it wasn't "Go" (higher case G and lower case O). To make sure you detect all forms of GO no matter what the case you change the user input to highercase or lowercase letters with either the UPPER$() or LOWER$() commands.
To avoid using GOTO you can use DO/LOOPs to keep the user within the loop till the right conditions are met to leave the DO/LOOP with the EXIT command. Once the EXIT has been seen it goes to the line just under the LOOP to continue the program.
print " "
do
` Get the user input
INPUT "type go > ",InputString$
` Make the user input higher case
InputString$=upper$(InputString$)
` Check if the command is right and leave the DO/LOOP
if InputString$="GO" then exit
` Show that the command is wrong
print "Command Unknown"
loop
print "test"
wait key
You should check out TDKs tutorials to learn the basics of Darkbasic Pro.
http://forum.thegamecreators.com/?m=forum_view&t=99497&b=10