In SX Microcontrollers, SX/B Compiler and SX-Key Tool, kvwood wrote:

Assuming that Switch1 and Switch2 can have a value of either 0 or 1:

AND
-----------
0 & 0 = 0
0 & 1 = 0
1 & 0 = 0
1 & 1 = 1

So, the answer can only be 0 or 1, based on the inputs. You need both inputs to be 1 to get a 1 on the output.


If closing the switches produces a zero, you could use NOR (Not OR):

NOR
-----------
0 | 0 = 1
0 | 1 = 0
1 | 0 = 0
1 | 1 = 0

Here, both inputs need to be 0 for a 1 on the output. NOR isn't a keyword operator, so you would need to use OR + NOT:

OR + NOT
------------
0 | 0 = ~0
0 | 1 = ~1
1 | 0 = ~1
1 | 1 = ~1

Generally speaking, in Boolean logic, 1 = On/Open/Yes/True/etc., and 0 = Off/Closed/No/False/etc. NOT inverts the value, so NOT 0 = 1, NOT 1 = 0. Boolean logic will always reference a value of 0 or 1.

The counter that you're using is doing essentially the same thing as the Boolean logic: keeping track of the states of two inputs to determine an output value. Boolean logic also scales very well. If you had 100 switches ANDed, they would only produce a 1 output if ALL the inputs = 1. 

Here is a website that shows some basic gates: [url]http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/gate.html#c1[/url]

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