fundamental_logic_gates.markdown

Fundamental Logic Gates

Computers are built on logic gates. Say we want to start designing hardware using Ruby. We'd need to first implement those fundamental gates.

Challenge

AND

An AND gate has two or more inputs. The output is "high" (1) if and only if all the inputs are high. Assume that all inputs are "low" (0) by default.

Build a two-input AND gate like the below. Your implementation should not make use of the built in Ruby AND functionality (&&, &, and).

gate = And::Double.new
gate.input_a = 1
gate.input_b = 1
gate.output # => 1
gate.input_b = 0
gate.output # => 0

Then use your two-input ANDs to build a three-input AND:

gate = And::Triple.new
gate.input_a = 1
gate.input_b = 1
gate.output # => 0
gate.input_c = 1
gate.output # => 1
gate.input_a = 0
gate.output # => 0

Then create a class which can dynamically build multi-input gates using only your two-input gate as the building block:

gate = And::Multi.new(4)
gate.input_a = 1
gate.input_b = 1
gate.input_c = 1
gate.output # => 0
gate.input_d = 1
gate.output # => 1
gate.input_b = 0
gate.output # => 0

Heads up that this is quite difficult.

OR

An OR gate has two or more inputs. The output is "high" (1) if one or more of the inputs are high.

Build a two-input OR gate like the below. Your implementation should not make use of the built in Ruby OR functionality (||, |, or).

gate = Or::Double.new
gate.input_a = 1
gate.input_b = 0
gate.output # => 1
gate.input_a = 0
gate.output # => 0

Then use your two-input OR to build a three-input OR:

gate = Or::Triple.new
gate.input_a = 0
gate.input_b = 0
gate.output # => 0
gate.input_c = 1
gate.output # => 1
gate.input_c = 0
gate.output # => 0

Then create a class which can dynamically build multi-input gates using only your two-input gate as the building block:

gate = Or::Multi.new(4)
gate.input_a = 0
gate.input_b = 0
gate.input_c = 0
gate.output # => 0
gate.input_d = 1
gate.output # => 1
gate.input_d = 0
gate.output # => 0

Heads up that this is also quite difficult.