Making an Adder
The XOR gate is essentially a one bit adder,
with an input of two 0's the output is 0 0+0
with an input of a 1 and a 0 the output is 1 1+0
with an input of two 1's the output is 0 1+1 = 10, requires carry out
to expand the adder and add more bits, carrying out and carrying in is necessary
the obvious approach to this is through one of the simplest gates: the AND gate. Using an AND gate attached to the same inputs being used by the XOR will output a 1 if and only if both inputs are on, ex if only one input or no input is on the and won't allow flow but if both inputs are on (which means rounding will be necessary) then it will output a 1 which would represent the 1 in two (10).
Using the carryout is much more difficult than just getting it. To use it one approach is to take the inputs from the second digit of the numbers being added and put them into and XOR and AND gate like mentioned previously. The output of the 2nd digit's XOR should then be ran into a second XOR that uses the output from the and gate of the first digit. Then using an AND gate on the XOR connected to the first and second outputs, and the carry out of the second digits, put both into an OR gate, which if either of them is on will be the carry in for the next digit.
good example here:
https://youtu.be/D0S4MEY4NeQ?t=13m10s
with an input of two 0's the output is 0 0+0
with an input of a 1 and a 0 the output is 1 1+0
with an input of two 1's the output is 0 1+1 = 10, requires carry out
to expand the adder and add more bits, carrying out and carrying in is necessary
the obvious approach to this is through one of the simplest gates: the AND gate. Using an AND gate attached to the same inputs being used by the XOR will output a 1 if and only if both inputs are on, ex if only one input or no input is on the and won't allow flow but if both inputs are on (which means rounding will be necessary) then it will output a 1 which would represent the 1 in two (10).
Using the carryout is much more difficult than just getting it. To use it one approach is to take the inputs from the second digit of the numbers being added and put them into and XOR and AND gate like mentioned previously. The output of the 2nd digit's XOR should then be ran into a second XOR that uses the output from the and gate of the first digit. Then using an AND gate on the XOR connected to the first and second outputs, and the carry out of the second digits, put both into an OR gate, which if either of them is on will be the carry in for the next digit.
good example here:
https://youtu.be/D0S4MEY4NeQ?t=13m10s
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