4-BIT BINARY FULL ADDER WITH FAST CARRY The SN54 / 74LS83A is a high-speed 4-Bit binary Full Adder with internal carry lookahead. It accepts two 4-bit binary words (A1–A4, B1–B4) and a Carry Input (C0). It generates the binary Sum outputs R1–R4) and the Carry Output (C4) from the most significant bit. The LS83A operates with either active HIGH or active LOW operands (positive or negative logic). The SN54/74LS283 is recommended for new designs since it is identical in function with this device and features standard corner power pins.