The following diagram shows a visual representation of a bank of 16 cameras connected, through multiplexer and switch box to a keypad with joy stick.  Using the keypad, any of the cameras can be remotely controlled.  Those pictured are pan tilt cameras with 360 degree horizontal movement and 180 degree vertical movement.  They also have zoom capability.  When connected to a DVR these components create a system that is superior to VCR systems in every way.