'A program that performs visual effects similar to the cascade virus
'It is NOT A VIRUS!!!!

delay = 1000
IF COMMAND$ <> "" THEN delay = VAL(COMMAND$): c = 1

'Read the screen
FOR l = 1 TO 25
FOR c = 1 TO 80
a$ = CHR$(SCREEN(l, c))
scrn$ = scrn$ + a$
NEXT c
NEXT l

'Put some text on the screen
'test = 1
IF test = 1 THEN
CLS
PRINT "Hello there everyone"
PRINT "This is a screen full of test test for this progam"
PRINT "It is irrelivent what it says,                      or where it says it!"
PRINT "It just needs to be there"
PRINT
PRINT
PRINT "                                                 A little over here, I think!"
LOCATE 15, 1
PRINT "...and down here!"
PRINT
PRINT
PRINT "This program will make all the letters drop to the bottom of the screen!"
END IF

PRINT "THIS_IS_NOT_A_VIRUS!!_(Press_any_key_to_Stop_and_restore_the_screen)"
'Now the clever bit...
l = 23
c = 80
cl = 23
cc = 80

char:
a = 3
IF l > 7 THEN a = 2
IF l > 15 THEN a = 1
IF c = 1 THEN a = 1
a$ = CHR$(SCREEN(l, c))
IF a$ = " " THEN GOTO nxtchar
b$ = CHR$(SCREEN(l + a, c))
IF b$ <> " " THEN GOTO nxtchar
'drop the letter
LOCATE l, c
PRINT " ";
LOCATE l + a, c
PRINT a$;
IF INKEY$ <> "" THEN GOTO nd
FOR z = 1 TO delay: NEXT z
l = l + a
IF l >= 24 THEN l = cl: GOTO nxtchar
GOTO char

nxtchar:
c = c - 1
IF c = 0 THEN c = 80: cl = cl - 1
IF cl = 0 THEN LOCATE 25, 1: SLEEP 3: a$ = INKEY$: GOTO nd
l = cl
GOTO char

nd:
CLS
PRINT scrn$;