Shifting Maze

This program prints a maze on a 1K ZX81. Run in SLOW for best effect.

  10 FOR R=0 TO 19
  20 FOR C=0 TO 19
  30 PRINT CHR$(INT (RND+.5)*2+3);
  40 NEXT C
  50 PRINT
  60 NEXT R

For a shifting maze, add:

   5 PRINT AT 0,0;
  70 GOTO 5

To exit, press BREAK.