PROGRAM PATTERN; {this demo prints a pattern of characters on the screen,}
{in normal and inverse video}
CONST
  NORM = 0; {screen attribute}
  REVERSED = 7;
VAR
  CHARACT : CHAR;
  ATTRIBUTE : INTEGER;
  XPOSITION,YPOSITION : INTEGER;
  DUM1,DUM2:INTEGER;
  

PROCEDURE SWITCH_ATTR; {between normal and reversed video}
BEGIN
  CASE ATTRIBUTE OF
    NORM : ATTRIBUTE := REVERSED;
    REVERSED : ATTRIBUTE := NORM;
  END;
  WRITE(CHR(27), '[', ATTRIBUTE:1, 'm');
END;

PROCEDURE SETCURSOR(XPOS, YPOS : INTEGER);
BEGIN
  CURSOR(XPOS+YPOS-16,YPOS); 
  DUM1 := XPOS;
  DUM2 := YPOS;
END;



BEGIN {-----------------main line of program------------------------}
  
  {write a pattern of characters on the terminal, varying the attribute
  {and position.}
  
  CLS;
  ATTRIBUTE := NORM;
  FOR XPOSITION := 10 TO 30 DO
     BEGIN
        SWITCH_ATTR;
        FOR YPOSITION := 16 TO 22 DO
           BEGIN
              CHARACT := CHR(32+XPOSITION);
              SETCURSOR(XPOSITION, YPOSITION);
              WRITE(CHARACT);
           END;
     END;
   ATTRIBUTE := REVERSED;
   SWITCH_ATTR;
END.