1 REM ==============================
2 REM ITERATIVE DESIGN 64
3 REM HERES A C-64 VERSION
4 REM BUT PAINFULLY SLOW !!
5 REM CODED BY P-D/TIDE-AMIGA IN 98
6 REM ==============================
7 REM USE 128 VERSION FOR SPEED.
8 REM ==============================
10 GOSUB 1000 :REM INITIALISE GRAPHICS
20 FOR X=0 TO 319
40 S=1+TAN(0.005*X)
50 FOR Y=0 TO 199 STEP S
60 GOSUB 2000 :REM SET PIXEL AT X,Y
70 NEXT Y
80 NEXT X
90 GET A$ : IF A$="" THEN 90
100 GOSUB 3000
110 END
950 REM ******************************
960 REM
970 REM >>>INITIALISE BIT MAP MODE<<<
980 REM
990 REM SET & RESET BIT FUNCTIONS
1000 DEF FNSB(N)=PEEK(MM) OR 2^N
1010 DEF FNRB(N)=PEEK(MM) AND (255-2^N)
1020 VV=53248 :REM VIC-II REGISTER 0
1030 :REM >>>PUT BITMAP AT 8192<<<
1040 MM=VV+24 : POKE MM,FNSB(3)
1050 :REM >>>SELECT BITMAP MODE<<<
1060 MM=VV+17 : POKE MM,FNSB(5)
1070 BASE=8192 :REM STARTBITMAP MEMORY
1080 :REM >>>CLEAR BITMAP<<<<<
1090 GOSUB 4000
1100 :REM SELECT COLOURS C1 & C0
1110 C1=1:C0=0:CC=16*C1+C0
1120 FOR MM=1024 TO 2023 :POKE MM,CC:NEXT
1140 RETURN
1150 :
1970 REM ==============================
1980 REM > TURN ON PIXEL AT (X,Y) <<<<<
1990 REM ==============================
2000 BIT=7-(X AND 7)
2010 MM=BASE+320*INT(Y/8)+8*INT(X/8)+(Y AND 7)
2020 POKE MM,FNSB(BIT)
2030 RETURN
2040 :
2970 REM ==============================
2980 REM >>>RESET BITMAP MODE<<<<<<<<<<
2990 REM ==============================
3000 MM=VV+17 : POKE MM,FNRB(5)
3010 REM RESTORE SCREEN MEMORY BASE
3020 MM=VV+24 : POKE MM,FNRB(3)
3030 RETURN
3960 :
3970 REM ==============================
3980 REM >>>CLEAR BITMAP SCREEN<<<<<<<<
3990 REM ==============================
4000 FOR M=828 TO 828+43
4010 READ B : POKE M,B
4020 CK=CK+B
4030 NEXT
4040 IF CK<>5133 THEN PRINT "DATA ERROR IN LINES 4060 - 4110" : STOP
4050 SYS 828: RETURN
4060 DATA 76,68,3,0,32,31,64,0
4070 DATA 173,63,3,133,251,173,64,3
4080 DATA 133,252,174,65,3,160,0,173
4090 DATA 67,3,136,145,251,208,251,230
4100 DATA 252,202,48,7,208,244,172,66
4110 DATA 3,208,239,96