1060 CLS:CLEAR2000:FILES:A$="Which file to sort: ":GOSUB2030
1140 INPUTF$:IFMID$(F$,LEN(F$)-2,1)<>"."THENF$=F$+".DO"
1150 A$="Lines in Header ":GOSUB2030
1170 INPUTM: OPENF$FORINPUTAS1
1200 FORJ=1TOM+1:LINEINPUT#1,Z$:NEXT:CLS
1280 PRINT"----.----1----.----2----.----3----.----4";
1290 PRINTZ$
1300 A$="Begin at position: ":GOSUB2030
1310 INPUTB:IFB=0THEN1300
1320 A$="End at position: ":GOSUB2030
1330 INPUTE:N=M+1
1430 N=N+1
1440 LINEINPUT#1,Z$:IFEOF(1)THENGOTO1470
1460 GOTO1430
1470 CLOSE
1480 DIMD$(N):DIMY$(M):OPENF$FORINPUTAS1
1490 IFM=0THENGOTO1550
1500 FORJ=1TOM:LINEINPUT#1,Y$(J):NEXT
1550 FORI=M+1TON:LINEINPUT#1,D$(I):NEXT
1580 CLOSE1:GOSUB3030
1645 KILLF$:OPENF$FOROUTPUTAS1
1648 IFM=0THENGOTO1660
1650 FORJ=1TOM:PRINT#1,Y$(J):NEXT
1660 FORI=M+1TON:PRINT#1,D$(I):NEXTI
1690 CLOSE:MENU
2030 PRINT@240,STRING$(40,32);
2040 PRINT@240,A$;
2050 RETURN
3030 Z5=N
3040 Z5=INT(Z5/2):IFZ5=0THEN3190
3060 Z2=1:Z3=N-Z5
3070 Z1=Z2
3080 Z4=Z1+Z5
3100 IF(MID$(D$(Z1),B,(E-B)+1))<(MID$(D$(Z4),B,(E-B)+1))THEN3160ELSE3120
3120 Z6$=D$(Z1):D$(Z1)=D$(Z4):D$(Z4)=Z6$
3130 Z1=Z1-Z5:IFZ1<1THEN3160
3150 GOTO3080
3160 Z2=Z2+1
3170 IFZ2>Z3THEN3040
3180 GOTO3070
3190 RETURN