6 November – Day 21
Turing Machine is a fundamental CS concept
Turing – Alan Turing ~1900-1955, British mathematician
wanted to solve the ‘universal computation’ problem
TM is a mathematical model of computation (collection of rules)
Importance of TM comes from the Turing Thesis which says:
TM is the “simplest” computer – anything a computer can do can be
done by a TM!
Follow handout (chapter 9 of Peter Linz, MCS 825 text)
p. 230 –
draw tape – tape consists of cells which may contain a symbol
draw read/write head –
I/O
- - - - -
control unit Processing
[note: Linz moves read/write head while Dewdney will move the tape]
TM model (picture fig 9.1)
Control unit is really a black box
“Outward” appearance, operation is simple
1. Move tape R or L
2. Read symbol off of tape
3. Write a new symbol on the tape
(tape is storage)
Power of a TM comes from what’s “inside” the control unit
- a “state machine”
Control unit
Q = {set of internal states}
q0 = initial state
F = final state(s)
delta = transition function
Control unit of a TM is specified by (key) state transition functions,
delta
CSC 490 Course Notes and Outline, © Dr. Gary Locklair, Fall 2006
