Wolfram's (2, 3) Turing Machine as an Universal TM with an Infinite Tape

gistfile1.txt

# (2,3) Turing Machine as an UTM

from time import sleep

# (state,symbol) => (state,symbol,head)
delta = {(0,0): (1,1, 1),
         (0,1): (0,2,-1),
         (0,2): (0,1,-1),
         (1,0): (0,2,-1),
         (1,1): (1,2, 1),
         (1,2): (0,0, 1)}

state, tape, head = 0, [0], 0

ds, space = {0: ' ', 1: '.', 2: '#'}, 40
while True:
    t = delta[(state,tape[head])]
    state, tape[head], head = t[0], t[1], t[2] + head
    if head >= len(tape):
        tape.append(0)
    elif head < 0:
        tape.insert(0, 0)
        head += 1
        space -= 1
    for _ in range(space): print(' ', end='')
    for s in tape: print(ds[s], end='')
    print('\r', end='')
    sleep(0.008)