NEMA$ = "$GPRMC,000004,V,3714.6284,N,12146.9181,W,0.000,0.0,290697,15.4,E*4C"
PRINT " " + NEMA$
chksum = ASC(MID$(NEMA$, 2, 1))

FOR x = 3 TO LEN(NEMA$) - 3
chksum = ASC(MID$(NEMA$, x, 1)) XOR chksum
NEXT x

PRINT " NEMA Checksum is " + HEX$(chksum)