80 PRINT "THIS IS THE SUBROUTINE BEFORE IT IS": PRINT "MODIFIED"
90 GOSUB 200
100 REM MAKE THE SWAP
110 CALL 38000(290,330,SA$,NA$,SB,NB)
120 HOME : PRINT "THIS IS THE SBROUTINE AFTER THE SWAP": PRINT "BUT BEFORE IT HAS BEEN EXECUTED"
130 GOSUB 200
140 GOSUB 320
150 CALL 38000(290,330,NA$,SA$,NB,SB)
160 HOME : PRINT "THIS IS THE SUBROUTINE AFTER IT HAS": PRINT "BEEN EXECUTED. NOTE THAT THE VALUES OF": PRINT "SA$ AND SB HAVE NOT CHANGED, BUT THAT": PRINT "NA$ AND NB HAVE."
170 GOSUB 200
180 END
190 REM LIST THE SUBROUTINE
200 PRINT : LIST 290 -330
210 PRINT : PRINT "THE VALUES OF THE VARIABLES ARE:"
220 PRINT "SA$";: HTAB 5: PRINT SA$
230 PRINT "SB";: HTAB 5: PRINT SB
240 PRINT "NA$";: HTAB 5: PRINT NA$
250 PRINT "NB";: HTAB 5: PRINT NB
260 VTAB 23: PRINT "TYPE 'RETURN' TO CONTINUE ";
270 INPUT "";C$: IF C$ < >"" THEN 260
280 RETURN
290 REM THIS IS THE SUBROUTINE WHICH WILL BE CHANGED