Contributor: BRANDON SNEED
#DATA $NAME "An Introduction to Boolean Arithmetic" / $AUTHOR "Light Ray" / $VERSION 001 / $DATE 950709 / $TYPE { TEXT ASCII
CRLF } #DATA
********************************************************
* *
* An Introduction To *
* *
* Boolean Arithmetic *
* aka Binary Math *
* *
* by *
* *
* Light Ray *
* *
********************************************************
NOTE: This refers to "binary arithmetic" as in arithmetic involving
the manipulation of binary bits, not necessarily arithmetic involving
two operands.
PREREQUISITE: NumberBases.* / NUMBASES.*
The following operations will be summarized in this
document: NOT, AND, NAND, OR, NOR, and XOR.
//===================\\
|| SIMPLE OPERATIONS ||
\\===================//
The NOT, AND, OR, and XOR operations are "atomic." That is, these are
the simplest operations and any other operation can be "built" using
them.
+-------------------+
| The NOT Operation |
+-------------------+
NOT is sometimes known as the "Inverse" operation.
NOT simply reverses the state of all bits. A one becomes a zero and
a zero becomes a one.
The expression "NOT A" is written as "A" with an overscore. (an overscore
is a horizontal line above the letter).
+--------------+--------------+
| Input (A) | Output (B) | _
+--------------+--------------+ B = A
| 0 | 1 |
| 1 | 0 |
+--------------+--------------+
The converse of a not operator is true. If A = NOT B, then B = NOT A.
+-------------------+
| The AND Operation |
+-------------------+
The and operation is a binary operator. It takes two parameters, usually
in the form "a AND b".
AND results in 1 only when both operands are 1, otherwise it results in
zero.
AND is sometimes written as a dot or multiplication sign.
Here is the truth table for C = A AND B
+--------------+--------------+--------------+
| Input (A) | Input (B) | Output (C) |
+--------------+--------------+--------------+
| 0 | 0 | 0 | C = A AND B
| 1 | 0 | 0 | C = A * B
| 0 | 1 | 0 |
| 1 | 1 | 1 |
+--------------+--------------+--------------+
+-------------------+
| The OR Operation |
+-------------------+
The OR operation is a binary operator. It takes two parameters, usually
in the form "a OR b".
OR results in 1 when at least one input is 1. This can be rephased to
say that the output is 0 only when both inputs are zero, otherwise it
is one.
OR is alternatively written as a plus sign.
Here is the truth table for C = A OR B
+--------------+--------------+--------------+
| Input (A) | Input (B) | Output (C) |
+--------------+--------------+--------------+
| 0 | 0 | 0 | C = A OR B
| 1 | 0 | 1 | C = A + B
| 0 | 1 | 1 |
| 1 | 1 | 1 |
+--------------+--------------+--------------+
+-------------------+
| The XOR Operation |
+-------------------+
XOR is a binary operation and is a derrivative of the OR operator.
XOR stands for "EXCLUSIVE OR", meaning that it results in ONE if and
only if either operand is one, but results in zero of neither or both
operands are one.
XOR is alternatively written as a plus enclosed by a circle, written
in ASCII as a plus in parenthesis.
+--------------+--------------+--------------+
| Input (A) | Input (B) | Output (C) |
+--------------+--------------+--------------+
| 0 | 0 | 0 | C = A XOR B
| 1 | 0 | 1 | C = A (+) B
| 0 | 1 | 1 |
| 1 | 1 | 0 |
+--------------+--------------+--------------+
//===================\\
|| COMLEX OPERATIONS ||
\\===================//
These operations may be built using the other operations.
+--------------------+
| The NOR Operation |
+--------------------+
A NOR B is one only when (A==0) and (B==0).
[ "==" is read "is". (A==B) is true (1) when A equals B, otherwise
it is false (0). ]
if C = A NOR B
then C = NOT (A OR B)
C = NOT (A OR B) is alternatively written as A+B with an overscore:
_______
C = (A + B)
+--------------+--------------+--------------+
| Input (A) | Input (B) | Output (C) |
+--------------+--------------+--------------+
| 0 | 0 | 1 | C = NOT (A + B)
| 1 | 0 | 0 | _______
| 0 | 1 | 0 | C = (A + B)
| 1 | 1 | 0 |
+--------------+--------------+--------------+ C = (A==0) AND (B==0)
+---------------------+
| The NAND Operation |
+---------------------+
if C = A NAND B
then C = NOT (A AND B)
+--------------+--------------+--------------+
| Input (A) | Input (B) | Output (C) |
+--------------+--------------+--------------+
| 0 | 0 | 1 | C = NOT (A * B)
| 1 | 0 | 1 | _______
| 0 | 1 | 1 | C = (A * B)
| 1 | 1 | 0 |
+--------------+--------------+--------------+ C = NOT ((A==1) AND (B==1))
---------------------------------
END
---------------------------------
This was typed and editted by Light Ray at the Digital Forest BBS,
which may be reached at +1 (714) 586-6142. It is located in
Mission Viejo, California, United States of America. This document
is based on Explorer Post 340 "lab notes" by "rlh" dated 5/10/95.
Please send any comments, suggestions, compaints, or addittions to
me at dr261@cleveland.freenet.edu, even if all you say is "I read
your file." I may also be reached at 1:103/925, 66:714/10, or
50:100/505.
Light Ray
Written by Tobin Fricke sometime in 1995. Feel free to contact me.
My email addresses are: tobin@mail.edm.net, fricke@roboben.engr.ucdavis.edu,
and dr261@cleveland.freenet.edu. You should be able to contact me via one
of those.