4-bit Binary Full Adder

The HD74LS283 adder is electrically and functionally identical to the HD74LS83A, respectively; only the arrangement of the terminals has been changed.

This improved full adder performs the addition of two 4-bit binary words.

The sum (Σ) outputs are provided for each bit and the resultant carry (C4) is obtained from the fourth bits generating the carry term in then nanoseconds.

The adder logic, including the carry, is implemented in its true form.

End around carry can be accomplished without the need for logic or level inversion.