For my final year degree project I am going to
build an LED display matrix,capable of displaying
moving messages. Some sort of Microprocessor
system is needed to control the display matrix.
Because of the multiplexing method that is going
to be used to control the display,a fast PIC with
the following facilities is required :-

- plenty of I/O lines.

- an A/D converter (as it's also going to be
  connected to a temperature sensor).

- Serial comms facilities to allow connection to
  a PC via RS 232 serial port.

- It must be capable of accessing external RAM as
  this is where the binary patterns representing
  the message will be stored.

I would appreciate any recommendations on what
type of PIC would be most suitable for this
application.