DOCUMENTATION FOR MAGIC1.BAS PROGRAM
WRITTEN BY JAMES H. BURNESS, CIS [73637,202]
*** for more details, see August 1986 Scientific American ***
>>>>>>>>> FOR BEST READABILITY, RUN IN LOW RESOLUTION <<<<<<<<<<<
This program "reads the mind" of a spectator and guesses a card
which the spectator has chosen from a deck. In the following
discussion, the performer of the trick is the computer's "master"
and the "spectator" is the one who picks the card (the performer
also looks at the card, but doesn't make it obvious that he has
seen it).
The trick is that the performer's response to each question posed
by the computer gives the answer to the NEXT question. The
performer answers either "yes" or "yes"
to the computer's questions, but he presses the space bar quietly
so that the spectator doesn't notice it. This is best done by
resting the thumb on the space bar and using the middle or ring
finger to press the return key.
[Note: The spectator is prompted for his name, then is told that
his typing on the keyboard will "confuse" the computer. He is
asked to pick a card, then to let the "master" (performer) type
the responses at the keyboard. There is a prompt to press the
return key. The "master" should press (again,
pressing the space bar casually). If the SPECTATOR presses
(without having pressed first), the computer
tells him/her that it knows its master was not at the keyboard.
The spectator is quite surprised at this revelation!!]
The performer answers the first question with a simple "yes" if
the card selected is black. If it is red, he answers with
"yes". The next question is answered with "yes" if the card
is a club (or diamond), and "yes" for a spade or heart. The
way to remember this is to remember that a 3-character response
(yes) codes for the smaller alphabetic response (black < red) and
the 4-character response (yes) codes for the larger
alphabetic response (spade > club, and heart > diamond). The same
reasoning works for determining the value of the card. Refer to
the following table:
"yes" response "yes response
-------------------- ---------------------
black red
club (or diamond) spade (or hearts)
8 or less 9 or more
Ace through 4 5 through 8
9 through Queen King
Ace or 2 3 or 4
5 or 6 7 or 8
9 or 10 J or Q
Ace two
three four
five six
seven eight
nine ten
Jack Queen
Example: spectator chooses the four of spades....
Computer Question Performer's response MEANING
IS THE SUBJECT CONCENTRATING? yes black
IS THE CARD BLACK? yes spade
IS THE CARD A SPADE? yes ace->8
IS THE CARD AN 8 OR LESS? yes ace->4
IS THE CARD A,2,3 OR 4? yes 3 or 4
IS THE CARD A 3 OR 4? yes four
IS YOUR CARD THE FOUR OF SPADES? N/A
The spectator sees only the screen, which shows that the computer
has correctly guessed that the card was black, that it was a
spade, that it was an 8 or less, etc. Quite an effective mind-
reading exercise!!!
jhb 8/5/86 [CIS 73637,202]