740REM "VIRUS" TYPE THING 750X=RND(39):Y=RND(29) 760IF FNAT(X,Y)=" "THEN GOTO 750 770IF Y>=30 THEN GOTO 750 780IF FNAT(X,Y+1)<>" "THEN Y=Y+1:GOTO 770 790Q$=FNAT(X,Y) 800PRINTTAB(X,Y);" ";TAB(X,Y+1)Q$; 810IF Y=31 THEN 750 820Y=Y+1 830IF FNAT(X,Y)<>" "THEN 780 840DEFFNAT(Q,P):PRINTTAB(Q,P);:A%=135: =CHR$((USR(&FFF4) AND &FF00)DIV&100) 850RUN