Scramble

SCRAMBLE is a word-unscrambling utility that accepts a 3–7 character input word and generates every possible permutation of its letters, displaying each unique anagram on screen. It uses a random-selection deduplication technique: a working copy array W$ has used positions marked with “/” as a sentinel, and a separate C$() array (dimensioned to hold up to 200 strings of length B) tracks already-seen results to avoid duplicates. The permutation count for each word length (6, 24, 120, 720, 5040) matches n-factorial and is displayed alongside estimated runtimes. Screen layout reflows into columns via AT-coordinate arithmetic, wrapping to a new column when row 19 is reached. The program ends with a COPY/Continue prompt once all permutations for the given word length have been found.

Program Structure

The program is divided into clearly separated functional blocks:

1. Lines 5–10: REM headers and GO TO 900 to skip subroutines on startup.
2. Lines 140–250: Main permutation loop — iterates, calls the random-picker, and repeats.
3. Lines 260–445: Deduplication and display subroutine; checks new permutation against stored ones.
4. Lines 450–480: “End of List” handler — offers print or continue.
5. Lines 500–510: Screen-overflow handler — pauses, clears, redraws header.
6. Lines 800–810: Header-printing subroutine.
7. Lines 900–1000: Initialisation — border, title screen, INPUT, array dimensioning, and jump to permutation loop.
8. Lines 2000–2060: Factorial lookup table — sets T and prints expected count.
9. Line 9999: CLEAR : SAVE "SCRAMBLE" LINE 1 — save-with-autorun line, never reached during normal execution.

Permutation Algorithm

Rather than a recursive or iterative algorithm, the program uses a probabilistic random-selection approach:

• Array W$ is re-initialised from A$ at the start of each permutation attempt (lines 140–150).
• A random index R is chosen; if W$(R)="/" it retries (line 190), acting as a used-slot sentinel.
• The chosen character is appended to R$ and its slot set to "/" (lines 200–220).
• Once LEN R$ = B, a full permutation is assembled and passed to the deduplication subroutine.

This approach is not guaranteed to be efficient — it may spin on GO TO 180 many times for later characters — but it is simple to implement in BASIC. Because it is purely random, the same permutation may be generated many times before all are found, making 7-character words (“? hours”) extremely slow in practice.

Deduplication Subroutine (Lines 260–320)

The subroutine at line 260 walks array C$ linearly, comparing each stored string to the new permutation R$:

• If an empty slot (CODE C$(E)=32, i.e. a space-filled string) is found, the new permutation is stored there (line 290).
• If a match is found, GO SUB 350 handles display and scoring (line 300).
• The counter E increments each pass; there is no explicit upper-bound check, so if C$‘s 200-row limit is exceeded a Subscript out of range error would occur for very long runs.

Display and Layout

Words are printed at position AT X,Y. Column wrapping is managed at line 360:

• X increments each new word; when X=19, it resets to 2 and Y advances by B+1.
• When Y>28, the screen-overflow subroutine at line 500 fires, clearing the screen and resetting coordinates.
• A brief BEEP .03,34 sounds on each column wrap (line 360).

Notable Techniques and Idioms

• POKE 23658,8 sets the system variable FLAGS2 to enable caps-lock (so INPUT accepts uppercase letters without SHIFT).
• POKE 23609,100 sets REPDEL, increasing the keyboard repeat delay.
• SAVE "SCRAMBLE" LINE 1 on line 9999 saves the program with autostart at line 1 (which hits the REM and falls through to GO TO 900). This is a common distribution idiom.
• Factorial counts are hard-coded in both the title screen (line 940) and the lookup subroutine (lines 2000–2040) rather than computed, saving runtime at the cost of flexibility.
• The FLASH 1/FLASH 0 wrapping is used for attention-drawing prompts at lines 450 and 500.

Content

Appears On

Fort Worth TS2068 Club Library Tape

This tape is a compilation of programs from user group members (Robert Burton, David Baulch, Frank Bouldin, Chuck Dawson, Ryan

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Source Code

    5 REM  SCRAMBLE
    8 REM  © by F. Bouldin, 8/7/85; ALL RIGHTS RESERVED
   10 GO TO 900
  140 FOR C=1 TO B
  150 LET W$(C)=A$(C): NEXT C
  170 LET R$=""
  180 LET R=INT (RND*B)+1
  190 IF W$(R)="/" THEN GO TO 180
  200 LET R$=R$+W$(R)
  210 IF LEN R$=B THEN GO TO 245
  220 LET W$(R)="/"
  225 GO TO 180
  240 LET C$(C)=R$
  245 GO SUB 260
  250 GO TO 140
  260 LET E=0
  270 LET E=E+1
  275 PRINT AT 0,28;"     ";AT 0,28;E
  280 IF R$=C$(E) THEN RETURN 
  290 IF CODE C$(E)=32 THEN LET C$(E)=R$
  300 IF C$(E)=R$ THEN GO SUB 350
  310 IF C$(E)=R$ THEN RETURN 
  320 GO TO 270
  340 REM 
  350 IF B=6 AND X=2 AND Y=28 THEN GO SUB 500:
  355 LET S=S+1: IF B=6 AND X=2 AND Y=28 THEN GO SUB 500:
  358 PRINT AT X,Y;C$(E)
  360 LET X=X+1: IF X=19 THEN LET X=2: LET Y=Y+B+1: BEEP .03,34: IF Y>28 THEN GO SUB 500
  400 IF B=3 AND S=6 THEN GO TO 450
  410 IF B=4 AND S=24 THEN GO TO 450
  420 IF B=5 AND S=120 THEN GO TO 450
  430 IF B=6 AND S=720 THEN GO TO 450
  440 IF B=7 AND S=5040 THEN GO TO 450
  445 RETURN 
  450 PRINT FLASH 1;AT 20,9;" End of List "; FLASH 0;AT 21,0;"Press P to print, C to Continue"
  455 FOR N=1 TO 10: BEEP .05,26: NEXT N
  460 IF INKEY$="P" THEN COPY 
  470 IF INKEY$="C" THEN CLS : GO TO 10
  480 GO TO 460
  500 PRINT FLASH 1;AT 21,2;" Press any key to continue ": BEEP .1,23: PAUSE 0: CLS : GO SUB 800: GO SUB 2000: LET X=2: LET Y=0
  510 RETURN 
  800 PRINT AT 0,1;"Unscramble "; INVERSE 1;" ";a$;" "; INVERSE 0
  810 RETURN 
  900 REM  "S-C-R-A-M-B-L-E"
  902 REM  By F. Boukdin, 8-1-85
  904 REM  Adapted from program   by C. Inman in Dec '83 SYNTAX
  910 BORDER 5: PLOT 0,0: DRAW 0,175: DRAW 255,0: DRAW 0,-175: DRAW -255,0
  920 LET X=2: LET Y=0: POKE 23658,8: POKE 23609,100: LET S=0
  930 PRINT AT 3,7; FLASH 1;" S-C-R-A-M-B-L-E "; FLASH 0;AT 6,4;"Enter the Scrambled Word";AT 8,6;"(3 to 7 cha PAUSE acters)"
  940 PRINT AT 12,5;"Possible combinations";AT 13,5;"---------------------";AT 15,3;"3 Char = 6   (3 seconds)";AT 16,3;"4 Char = 24  (16 seconds)";AT 17,3;"5 Char = 120 (1 min 32 sec)";AT 18,3;"6 Char = 720 (10 min 45 sec)";AT 19,3;"7 Char = 5040 (? hours)"
  950 INPUT A$ : IF LEN A$<3 OR LEN A$>7 THEN GO TO 950
  960 CLS : GO SUB 800
  970 LET B=LEN A$: GO SUB 2000
  980 DIM C$(200,B)
  990 DIM W$(B)
 1000 GO TO 140
 2000 IF B=3 THEN LET T=6
 2010 IF B=4 THEN LET T=24
 2020 IF B=5 THEN LET T=120
 2030 IF B=6 THEN LET T=720
 2040 IF B=7 THEN LET T=5040
 2050 PRINT AT 0,21;"(";T;")"
 2060 RETURN 
 9999 CLEAR : SAVE "SCRAMBLE" LINE 1

Note: Type-in program listings on this website use ZMAKEBAS notation for graphics characters.