Radio Shack TRS-80

Chapter
24
AND & OR
In
classical
mathematics
(fancy words for simple ideas)
there exist
what
are
known as
the
"logical AND"
and
the
"logical
OR".
So the One Cow
Said
to
the Other Cow .
.
.
In Figure
1,
if
Gate
A AND
gate
B
AND gate
C
are open,
the
cow
can move from Pasture
# 1 to Pasture #2.
If
any gate is closed,
the
cow's
path is blocked.
PASTURE
#1
ft,
cow
,/
GATE A
/
GATEB
PASTURE #2
/
GATE C FIGURE 1
The
principle
is called "logical AND".
In Figure 2,
if gate X OR
gate
Y
OR
gate Z are
open,
then old Bess can
move
from Pasture
#3 to #4.
That principle is called "logical OR". These
ideas are
both pretty
logical. If the
cow can figure
them
out
surely
you
can!
PASTURE
#3
f^f
OLD BESS
PASTURE
#4
/gate X
t
c/gate
Y
1
gatez
FIGURE 2
Grit Your
Teeth
and
Prepare
to
Say
AAAAAGHH!!
Somewhere
in the misty
history
of classical
mathematics,
a budding genius dedicated the
symbol "X" to mean AND,
and
"+"
to mean
OR.
Ordinary
arithmetic
of
course uses "X"
to mean
multiply
and
"+"
to
mean
add. To
further
confuse the
matter, instead of "X", for
computers
we
use
"*"
to
mean
multiply.
Our
logical
AND symbol,
therefore, is
"*".
AAAAAAGH!!!!!
(I
told
you.)
By the way, this
cow's
name is Bessie.
K^
I
\
"*
?^%^
•
~;~^™;-~;
TCSSin-IT'S
ONLY
LOGICAL.'
-"./'."''-.;."' -- :.^-
:
^."
: ::i""-'-
|
.l
Now
don't forget.. . in "logical" computer
work:
*
means
AND
+
means OR
147