[root@cs turing]# ./add.vtm 
This script adds two numbers.  The format of the tape is:

	_1...1_1...1_

where 1...1 is a string of 1s.  The first string of 1s represents the
first number in unary, i.e., the number n is represented by a string of
(n + 1) 1s (e.g. 2 is represented by `111').  The second string of 1s
represents the second number in unary.  The `_' in the middle separates 
the numbers.  So an initial tape of `_111_111_' will add 2 and 2, and 
hopefully get `_11111___' (`11111' is 4 in unary).

Specify initial tape: _1111_111_
   0:  _<1>1 1 1 _ 1 1 1 _ : pass_first
   0:  _<1>1 1 1 _ 1 1 1 _ : pass_first
   0:  _ 1<1>1 1 _ 1 1 1 _ : pass_first
   0:  _ 1<1>1 1 _ 1 1 1 _ : pass_first
   0:  _ 1 1<1>1 _ 1 1 1 _ : pass_first
   0:  _ 1 1<1>1 _ 1 1 1 _ : pass_first
   0:  _ 1 1 1<1>_ 1 1 1 _ : pass_first
   0:  _ 1 1 1<1>_ 1 1 1 _ : pass_first
   0:  _ 1 1 1 1<_>1 1 1 _ : pass_first
   0:  _ 1 1 1 1<1>1 1 1 _ : pass_second
   0:  _ 1 1 1 1 1<1>1 1 _ : pass_second
   0:  _ 1 1 1 1 1<1>1 1 _ : pass_second
   0:  _ 1 1 1 1 1 1<1>1 _ : pass_second
   0:  _ 1 1 1 1 1 1<1>1 _ : pass_second
   0:  _ 1 1 1 1 1 1 1<1>_ : pass_second
   0:  _ 1 1 1 1 1 1 1<1>_ : pass_second
   0:  _ 1 1 1 1 1 1 1 1<_>: pass_second
   0:  _ 1 1 1 1 1 1 1 1<_>: delete1
   0:  _ 1 1 1 1 1 1 1<1>_ : delete1
   0:  _ 1 1 1 1 1 1 1<_>_ : delete2
   0:  _ 1 1 1 1 1 1<1>_ _ : delete2
   0:  _ 1 1 1 1 1 1<_>_ _ : HALT
   0:  _ 1 1 1 1 1 1 _<_>_ : HALT
[root@cs turing]#