Add string input interrupt from STDIN

bin/test.wasm

@@ -88,12 +88,22 @@ seti %A $900;
 seti %B $4;
 int $3;
 
-# Jump over the interrupt
+# Call a function
 call noop_function;
 
 # Echo a character
 int $4;
 int $0;
+
+seti %A $10; # newline
+int $0;
+
+# Echo a string
+seti %A $0;
+seti %B $10;
+int $5;
+int $3;
+
 exit;
 
 noop_function: