001 REM Jefferson Disk Cipher, tfurrows@sdf.org
  100 REM Setup the disks
  101
  104 DIM A$(16)
  105 A$(1)="PDN HCAUBKQXEOZVRMGYJSFTWIL"
  106 A$(2)="ECSGFONUHMR YXDZPTLQAJBWVKI"
  107 A$(3)="TYFPZJS UNBWLXQREACDIOHMVKG"
  108 A$(4)="XHTNOZSFUJKREDQAC MGPBLYWIV"
  109 A$(5)="CPOMQZA TRFBGIWDLVHESJUKNXY"
  110 A$(6)="SXCOFRKJZVEG BAPWDNIHLQMUTY"
  111 A$(7)="H CLKIOZFSUPGREDBNVTYMAJWQX"
  112 A$(8)="NTAJULBWZYCPDSR HVMIFGKOXEQ"
  113 A$(9)="MHWNPZVLXCYJRKUSOEFADI TBGQ"
  114 A$(10)="UVEZHPSDNAYLJQTXWFBG CKIROM"
  115 A$(11)="ICNTHWZE LRMSQFGDAKXYJBOVUP"
  116 A$(12)="SEMB QTFLPIOZCUKYVRDWXJHGNA"
  117 A$(13)="RFTJWUZV HIYQOSLCMEXGDKPNAB"
  118 A$(14)="EM FNZPGUQROYVXCBAHTISWDLKJ"
  119 A$(15)="QPSGZDLNCIOUJK EXRAYHWFMTVB"
  120 A$(16)="GSFYRQBDI ALKXPVUTZJONEWCHM"
  121
  150 PRINT "Enter message to encode/decode"
  151 INPUT M$
  152
  200 REM Loop through message and set the jefferson disks
  205
  210 FOR I = 1 to LEN(M$)
  215 C=C+1
  220 IF C>16 THEN C=1
  225 L = POS(A$(C),SUBSTR(M$,I,1),1)
  230 IF L < LEN(A$(C)) THEN PRINT SUBSTR(A$(C),L+1,LEN(A$(C))-L);
  235 IF L > 1 THEN PRINT SUBSTR(A$(C),1,L) ELSE PRINT SUBSTR(A$(C),1,1)
  240 NEXT i