here is the example code

' SERIN & SEROUT Commands
'
' Upper case serial filter.

Include "modedefs.bas" ' Include serial modes

SO con 0 ' Define serial out pin
SI con 1 ' Define serial in pin
B0 var byte

loop: Serin SI,N2400,B0 ' B0 = input character
If (B0 < "a") or (B0 > "z") Then print ' If lower case, convert to upper
B0 = B0 - $20
print: Serout SO,N2400,[B0] ' Send character
Goto loop ' Forever

thanks for any help