How do you interface 3-multiplexed 7-segment displays with 8051or5052or--53--54--55 microcontroller to display a random number from 000 to 999 with 1sec delay?

Answer 1

You should use a mechanism called persistance of vision for interfacing multiple seven segment displays.

here is tutorial for mulplexing displays using 8051 microcontroller.

http://www.shree-electronics.com/interfacing_multiple_7_segment_displays.htm