Boolean algebra is the algebra dealing with variables whose possible values are restricted to true and false. It is widely used in fields such as mathematics, computer engineering, and philosophy. Digital circuit design employs boolean algebra to concisely express the logical operations performed by digital circuits.
Digital circuits use wires carrying electric current to represent boolean truth values. "1" values (used to represent true) are indicated by the presence of an electric current, and the absence of one indicates "0" (representing false). In reality, the wire can experience any intermediate state between "on" and "off", due to ramp-up, ramp-down, or unintended small induced currents. Because of this, digital circuit designers use different designations for the state of a wire, all depending on voltage thresholds. "Low" and "high" occur when the voltage is very close to the maximum and minimum expected voltage, respectively. "High" maps to 1, and "low" maps to 0. The intermediate states include weak, high-impedance, don't-care, conflict, unassigned, and more. In this site, we will deal primarily with high and low, and none of the intermediate states.
Digital circuits use wires carrying electric current to represent boolean truth values. "1" values (used to represent true) are indicated by the presence of an electric current, and the absence of one indicates "0" (representing false). In reality, the wire can experience any intermediate state between "on" and "off", due to ramp-up, ramp-down, or unintended small induced currents. Because of this, digital circuit designers use different designations for the state of a wire, all depending on voltage thresholds. "Low" and "high" occur when the voltage is very close to the maximum and minimum expected voltage, respectively. "High" maps to 1, and "low" maps to 0. The intermediate states include weak, high-impedance, don't-care, conflict, unassigned, and more. In this site, we will deal primarily with high and low, and none of the intermediate states.