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Basic half-adder and full-adder circuitsDescriptionThe basic 1-bit half-adder and full-adder circuits.
The sum bit is calculated with XOR gates,
while the AND gates are used to check whether two (or more) inputs
are 1, which implies that the carry out bit must be set.
Click the input switches, or use the ('a','b','c') and ('d','e')
bindkeys to toggle the input values of the full- and half-adders.
Note that the carry calculation path shown in this applet
uses the direct AND-OR realization (because it is the easiest
However, as will become clear in the following applets,
the speed of the carry generation logic in large adders
is often performance critical.
Therefore, cheaper and faster implementations based on inverting
gates (NAND-NAND), complex gates, or even custom designed special
circuits are used in practice.
Run the applet | Run the editor (via Webstart)
Impressum | 24.11.06