The real time clock data is only expressed in 24 hours format. But you can easily display it as 12 hours with simple IF statement:
IF (TIME[1] > 12)
A$ = STR$(TIME[1]-12)+":"+STR$(TIME[2])+STR$(TIME[3])+" PM"
ELSE
A$ = STR$(TIME[1])+":"+STR$(TIME[2])+STR$(TIME[3])+" AM"
ENDIF
SETLCD 1,1, "Time = " + A$