[Alan Anderson]

To turn RS-232 serial data into numbers, I suppose you could design some sort of state machine out of discrete logic...but you really ought to be using a programmable computer with a serial port. Although building your own UAR/T might be a fun challenge, it's much easier and much less expensive to use what's already built in to most microcontrollers.

Bottom line: don't try to turn serial data into numbers yourself. Let the available hardware do it for you. Connect the receive pin to the incoming data, program the UAR/T for the proper bit rate, and read the incoming bytes as they arrive. Your first task should probably be to decide what kind of processor you have the ability to program, and then either to design a computer around it, or use an existing design like a BASIC Stamp or Gumstix system.