Hi,You can refer this | Microcontroller › 8051 › 8 player quiz buzzer using at89c51 › Hi,You can refer this October 7, 2015 at 11:53 am #13361 Prabakaran P MParticipant Hi, You can refer this links http://www.engineersgarage.com/microcontroller/8051projects/8-candidate-quiz-buzzer-AT89C51-circuit http://www.engineersgarage.com/contributions/8-contestant-quiz-buzzer-project-using-assembly-language