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AND
Abbreviation: A <SHIFT+N>
TYPE: Operator
FORMAT: <expression> AND <expression>
Action: AND is used in Boolean operations to test bits. it is
also used in operations to check the truth of both operands.
In Boolean algebra, the result of an AND operation is 1 only
if both numbers being ANDed are 1. The result is 0 if either or
both is 0 (false).
EXAMPLES of 1-Bit AND operation:
0
AND 0
------------
0 |
1
AND 0
------------
0 |
0
AND 1
------------
0 |
1
AND 1
------------
1 |
The Commodore 64 performs the AND operation on numbers in the
range from -32768 to +32767. Any fractional values are not used,
and numbers beyond the range will cause an ?ILLEGAL QUANTITY error
message. When converted to binary format, the range allowed yields
16 bits for each number. Corresponding bits are ANDed together,
forming a 16-bit result in the same range.
EXAMPLES of 16-Bit AND Operation:
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17
AND 194
--------------------------------------------
0000000000010001
AND 0000000011000010
--------------------------------------------
(BINARY) 0000000000000000
--------------------------------------------
(DECIMAL) 0
32007
AND 28761
--------------------------------------------
0111110100000111
AND 0111000001011001
--------------------------------------------
(BINARY) 0111000000000001
--------------------------------------------
(DECIMAL) 28673
-241
AND 15359
--------------------------------------------
1111111100001111
AND 0011101111111111
--------------------------------------------
(BINARY) 0011101100001111
--------------------------------------------
(DECIMAL) 15119
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When evaluating a number for truth or falsehood, the computer
assumes the number is true as long as its value isn't 0. When
evaluating a comparison, it assigns a value of -I if the result
is true, while false has a value of 0. In binary format, -1 is
all 1's and 0 is all 0's. Therefore, when ANDing true/false evaluations,
the result will be true if any bits in the result are true.
EXAMPLES of Using AND with True/False Evaluations:
50 IF X=7 AND W=3 THEN GOTO 10: REM ONLY TRUE IF BOTH X=7
AND W=3 ARE TRUE
60 IF A AND Q=7 THEN GOTO 10: REM TRUE IF A IS NON-ZERO AND
Q=7 IS TRUE
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