Would this work as the full code (forgive my ignorannce: I'm a newbie)?

Transmitter:
------------

define HSER_TXSTA 20h
define HSER_BAUD 2400

cmcon = 7

PORTSTATE var Byte
LASTSTATE var Byte
input PORTA.0
input PORTA.1
INput PORTA.2
input PORTA.3

Main:
PORTSTATE = PORTA & $0F
If (PORTSTATE <> LASTSTATE) then
LASTSTATE = PORTSTATE
Hserout [PORTSTATE]
Endif
Pause 10
Goto Main


Receiver
--------

define HSER_CLROERR 1
define HSER_RCSTA 90h
define HSER_BAUD 2400

cmcon = 7
PortState VAR byte
output PORTA.0
output PORTA.1
output PORTA.2
output PORTA.3
low PORTA.0
low PORTA.1
low PORTA.2
low PORTA.3

Main:
Hserin 20,Main, [PortState]
PortState = PortState ^ $0F
PORTA = Portstate
Goto Main