10 REM **************
20 REM * WRSFR Test *
30 REM **************
40 FOR R=0 TO 0FFH
50 WRSFR (90H)R : REM Write to Port 1
60 RDSFR (90H)A : REM Read from Port 1
70 PH0. R,"=",A,"  ",
80 NEXT 
