Question

B. a) Draw a half adder using only NAND gates. b) Describe how 3 to 8 line Decoder circuits works and indicate typical inputs and outputs. Also provide a carefully labeled "black box" diagram. ANS:

Answer 1

fnst tals Add using Nand gates: Truth Table : Inputoutput A B Sum camy O o 0101米 0 0 A4B8 A. (AB) 9 (b). 3 to 8 Decoder Decoder is a combiational cirait which tokes multiple inputs and gives muttiple out puts It takes binan dath of n igputs and gives an uniquie outputs. In oddftion to nput pins , ft has a enable pin. this enables the pin uwhen negoted. makes the cirauit tnactive. 3 to 8 decoder has 3 inputs , emble out puts ptn &

3 to 8 decoder Truth table Outputs Inputs 0 0 O O O O O 0 Block Box diagrom Circuit dtagram. 8 c 8 1o Yo 8 C 8 Decoder 4- уз-ABC 5 En 45 ABC En=1