pin diagram of 8051

Question 1

pin 40

Answer 1

Vcc power source usually its 5V dc

Question 2

pin 32-39

Answer 2

Port 0.0- Port 0.7 is an :
-> bi directional i/o port ( requires external pull up R for it to function as i/o)
-> lower order address and data bus signals are multiplexed in order to serve the purpose of external memory interfacing

Question 3

pin 21-28

Answer 3

port 2.0- port 2.7 is an :
additional i/o port where higher order bus signals are multiplexed with this quasi based bi directional port

Question 4

pin 20

Answer 4

Vss - Ground