Hi Ron,

A few things going on here.

You've set SO as a constant of 0, then later used SO as the SEROUT pin. That will put the Serial Output on PORTB.0. I'm not sure which PIC you're using, but it's probably not pin 13.

Variable declarations...
B0 = VAR BYTE
B1 = VAR BYTE
should not have equal signs in them.
B0 VAR BYTE
B1 VAR BYTE

I'm not sure what these two lines are for...
OUTPUT 13
HIGH 4
but they have no bearing on your program.

Try it like this
Code:
SO    VAR  PORTB.0   ' Or whichever pin you like
N2400 CON 4 
B0    VAR  BYTE
B1    VAR  BYTE
A     VAR  BYTE

B1 = "X"
FOR A=0 TO 15
    WRITE A,B1
NEXT A

FOR A=0 TO 15
    READ A,BO
    SEROUT SO,N2400,[#B0," "]
NEXT A
HTH,
    Darrel