4- BIT BINARY ADDER / SUBTRACTOR. MODEL IBL-DE-2 The general public thinks of digital devices as fast and accurate calculating machines. The calculator and digital computer are probably the reason for that. Arithmetic circuits are common in many digital systems. It will be found that rather simple combinational logic circuits (several gates connected) will add, subtract, multiply, and divide. This chapter will cover binary arithmetic and the way it is performed by logic circuits. Qty :